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An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel
Vaccine xxx (xxxx) xxx
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An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel John Boyle a, Lew Berman a, Glen J. Nowak b, Ronaldo Iachan a, Deirdre Middleton a,⇑, Yangyang Deng a a b
ICF, 530 Gaither Rd, Suite 500, Rockville, MD 20850, United States Grady College Center for Health & Risk Communication, 120 Hooper Street, University of Georgia, Athens, GA 30047, United States
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 7 December 2019 Accepted 9 January 2020 Available online xxxx Keywords: Survey research Nonprobability sampling Vaccine hesitancy Attitudes and beliefs
a b s t r a c t Introduction: It is important to quickly identify parent beliefs, intentions, and behaviors toward childhood vaccination, especially parents of children 19 to 35 months. This paper describes parental immunization beliefs, intentions, and behaviors; assesses the relationships between beliefs and intentions regarding child immunization and actual behaviors; and assesses whether beliefs, intentions, and/or behaviors varied across demographic subgroups. Methods: A sample of parents, ages 18 and older, from a mobile panel with people residing in the U.S. were invited to answer immunization behavior, intention, and belief questions using a smartphone app that was not vaccine specific. 10,000 panel members with a child under 18 were sent invitations. 1029 surveys were completed by a respondent with a child 19 to 35 months. The survey instrument replicated many NIS questions and had similar sequencing. Findings: Respondents reported that most children received all recommended vaccines, except flu vaccine, suggesting some may not understand the immunization schedule. Demographics closely associated with immunization behaviors were respondents’ education and household income. There is strong agreement that vaccines are effective, important to community health, and the child’s health. There is concern about the number of shots received, disease prevention, and ingredient safety. Some belief remains about vaccines causing learning disabilities. Positive beliefs about the benefits of childhood vaccines and concomitant risks vary with demographics. Conclusions: This survey provided insights into beliefs and behaviors of parents regarding childhood vaccination. It found evidence of differences in beliefs, particularly related to delaying or declining recommended childhood vaccinations. The survey was conducted in a few days and at lower cost than traditional methods. This serves as a model for health agencies where rapid results or inexpensive approaches are needed. Ó 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction Consistently high childhood immunization rates have greatly reduced the rates of death, disability, and illness from communicable diseases in the United States. However, recent U.S. outbreaks of childhood diseases related to unimmunized children have raised concerns about parental commitment to recommended immunization schedules [1]. Knowing parents’ beliefs and intentions regarding recommended childhood immunizations can help immunization programs and health care providers better address vaccination concerns and identify emerging issues, particularly if
⇑ Corresponding author at: 530 Gaither Road, Suite 500, Rockville, MD 20850, United States. E-mail address: [email protected] (D. Middleton).
valid and reliable data can be collected more regularly and costefficiently. The U.S. Centers for Disease Control and Prevention’s (CDC) National Immunization Survey (NIS) remains the national gold standard for measuring and tracking vaccination rates among children 19–35 months old on an annual basis. However, this survey does not involve regular assessment of parent beliefs or intentions regarding recommended immunizations. The NIS design obtains yearly immunization coverage for 60 geographic areas, fifty of these are states, one is the District of Columbia, and nine involve predefined local areas [2]. Study data are released at least a year after field work is completed. Thus, the NIS is not temporally or geographically sensitive to discover rapidly emerging immunization concerns or identifying beliefs that may be related to vaccination hesitancy. Moreover, since the population proportion of the target population – parents of children aged 19 to 35 months - is low (less
https://doi.org/10.1016/j.vaccine.2020.01.032 0264-410X/Ó 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx
than 5% of all U.S. households) and the sample size required to identify and assess behavior, intention, and belief differences in demographic subgroups is large, traditional telephone-based survey methods are very expensive for these assessments. It is thus important to identify and assess the value of other approaches, such as ones that involve geographically or demographically representative non-probability sampling frames. For example, the CDC has used non-probability samples since 2008 to assess immunization beliefs and behaviors related to seasonal flu vaccination among pregnant women and health care workers [3,4]. Over the last decade, the emergence of the Internet and the common use of mobile phones and more recently smartphones, has created new, and more rapid, capabilities for conducting survey research, particularly among individuals in the target population for early childhood vaccinations. Overall, the proportion of U.S. adults who own smartphones has grown from 35% in 2011 to 77% in 2018 [5]. Moreover, smartphone penetration exceeds 90% in the 18–49 year-old age cohort which contains almost all parents of children aged 19–35 months [5]. Smartphone software apps have been used to provide vaccine and vaccination schedule information to parents and to increase parents’ acceptance of MMR vaccine [6] and as part of mobile phone-based interventions to improve routine childhood immunization coverage, particularly in low- and middle-income countries [7,8]. A study in Canada used an immunization-related application to determine whether the use of a mobile immunization app was associated with the likelihood of reporting on-time vaccination in a cohort of 50 childbearing women [9]. The pervasive reach and use of smartphones open a potential pathway for research on childhood immunization beliefs, intentions, and behaviors that warrants consideration, particularly for more rapid or targeted assessments. Therefore, our research adopted this data collection strategy to address three central objectives: (1) describing parental immunization-related beliefs, intentions, and behaviors; (2) assessing the relationships between beliefs and intentions regarding child immunization and actual behaviors (i.e., refusals or delays in recommended vaccinations); and (3) assessing whether beliefs, intentions, and/or behaviors varied across various demographic subgroups. We believe this is the first study to use a smartphone panel and a software app to survey parents of children ages 19–35 months to quickly gain insights into their beliefs, intentions and behaviors towards recommended childhood vaccinations. 2. Research method A sample of parents, ages 18 and older, from the MFour allmobile consumer panel was invited to answer immunizationrelated behavior, intention, and belief questions. The survey was implemented between December 16 and 21, 2017, via the Surveys On The GoÒ mobile research app for Android or iOS smartphones. Those individuals who download the app, agree to the terms of service and create an account become panel members. The app allows panel members to receive invitations to surveys and to complete them in exchange for small financial incentives. On average, it took respondents 10 min to complete the survey. Respondents from all 50 states and the District of Columbia were represented in the final sample. This study and the processes within the study for the protection of human subjects were reviewed and approved by the ICF Institutional Review Board. 2.1. Sample selection The frame for this study was the MFour mobile panel, which was used to draw a non-probability sample of U.S. adults ages 18
and over with at least one child between the ages of 19 and 35 months old. At the time of the study, the MFour panel was comprised of approximately 2 million people. People in the full panel had to be age 13 and over, living in any of the 50 states, own a smartphone with Android or iOS, and have registered to receive and respond to survey opportunities using the Surveys On The GoÒ app. Individuals qualified for panel inclusion by completing a series of profiling questions and fraud detection measures. While the panel does not provide a comprehensive population frame or enable probability samples, for the general population, it is designed to provide national non-probability samples of adults that are geographically and demographically representative of the U.S. adult population. The sample drawn for this survey was large enough to detect differences in beliefs by sociodemographic characteristics and subpopulations, which is important for identifying potential differences in immunization-related beliefs, intentions, and behaviors across population segments. The MFour panel included members’ age, zip code, and whether there were children under 18 in the household. Thus, samples can be restricted to adults or specific geographic areas if desired. Importantly, the panel methodology enabled efficient targeting of a national sample of parents of children under 18 years old for the initial household screening. In this study, for instance, a national sample of 10,000 mobile panel members who were known to have a child under 18 years old in the household were sent the initial invitations to participate in the survey. Eligible adults who completed the survey earned one dollar for their participation. The amount of the reward for participation was included in the invitation but the purpose and subject matter was not. 2.2. Participant screening A total of 1029 surveys were completed by respondents who had a child aged 19 to 35 months old in their household. The survey program validated eligibility by requesting the month, day, and year of birth for each child reported. A software program calculated the actual age in months for each child, and only respondents who had an age-eligible child were invited to complete the rest of the survey. These eligible participants, in turn, were asked whether they were the person who knew the most about the health, doctor visits, and immunizations or shots that the target children had received. Almost all (97.3%) reported that they were the most knowledgeable. For purposes of comparability to the NIS, only the 1001 respondents who indicated they were the most knowledgeable adult in the household were included in the analyses. 2.3. Survey instrument The survey instrument replicated many survey questions as well as sequencing from the NIS in order to assess comparability of demographics and reported behaviors between the NIS and the panel sample. This included questions on the age of child, gender of child, race of child, respondent relationship to child, living arrangement, maternal education, and household income for direct comparisons to NIS estimates. However, we did not incorporate the NIS physician follow-up survey items as our study was focused on parental beliefs, intentions, and behaviors rather than verification of a child’s vaccination record. The survey also included questions related to respondents’ education and race/ethnicity, which along with household income, were used to identify and analyze demographic differences in parental immunization beliefs, intentions, and behavior rather than to conduct a comprehensive analysis of socio-economic health disparities. Childhood immunization behaviors were assessed using five measures. Two measures, received all recommended vaccines and flu vaccination in past year, were drawn from the NIS [10].
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
J. Boyle et al. / Vaccine xxx (xxxx) xxx
Two measures, delayed and refused childhood vaccines, were drawn from the six behavioral items in the Parental Attitudes and Childhood Vaccines (PACV) survey tool [11]. One item on future immunization intention was added. Seven immunizationrelated belief questions were drawn from 11 potential concerns assessed in the 2009 HealthStyles Survey of parents [12]. The seven items were nearly identical, but they were structured as four-point Likert scales in this survey. An additional three belief items - vaccines are effective, important for my child’s health, and important for the health of others in the community - were drawn from other questions in the same survey but used the same response categories as the other belief items in this study. A final belief question about the reliability and trustworthiness of information about vaccines from the government was added in the same format to complete the scale.
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compared to the NIS (35% vs. 41%). In both surveys, the average number of eligible children in the household was one, with approximately half male (51% vs. 52%). In our survey, respondents’ eligible children were more likely to be 24–29 months of age and nonHispanic white compared to the NIS (46% vs. 30% and 54% vs. 46%, respectively). Given that smartphone ownership in the U.S. is substantially higher in persons under 50, there was a smaller percentage of grandparents in our survey (2.4%) compared to the NIS (5.8%). Post-stratification weights for sample estimates were not applied in the analysis since the study’s primary objectives were to examine correlations between parents’ childhood immunization beliefs and behaviors as well as differences in beliefs and behaviors among demographic subpopulations (vs. to generate total population estimates). 3.2. Self-reported children’s immunization status
2.4. Statistical analyses The analyses focused on the objectives described earlier: (1) describing respondents’ childhood immunization-related beliefs, intentions, and behaviors; (2) assessing the relationships between beliefs and intentions regarding child immunization and actual behaviors (i.e., refusals or delays in recommended vaccinations); and (3) assessing whether beliefs, intentions, and/or behaviors varied across various demographic subgroups. To address these goals, the analyses were primarily (1) examinations of associations and correlations and (2) bivariate analysis of these different measures and covariates. Associations were assessed using Pearson correlation coefficient and non-parametric Spearman (rank) correlation where more appropriate. While confidence intervals for the estimates are not presented given the use of a non-probability sample, standard errors were calculated and are provided to give a sense of the spread of distributions. We also used Chi-squared tests for categorical variables to identify significant differences across subgroups.1 All analyses were conducted with SPSS Statistics (IBM, Armonk, NY) and SAS version 9.4 (SAS Institute, Cary, NC). 3. Results The following sections summarize results from our analyses specifically related to comparisons between this sample and the NIS national probability sample, the immunization practices of this population including child vaccination status and intent, immunization beliefs and how these vary across key demographic groupings. 3.1. Comparisons to the national immunization survey After correcting for any known differences in selection probabilities (e.g., disproportionate sampling for geographic strata in the NIS), survey samples are typically compared to population parameters to determine whether additional post-stratification weighting is required to correct for demographic biases. We initially compared the characteristics of the respondents and children from our unweighted survey sample to the characteristics of the weighted NIS sample to identify potential bias. The demographic characteristics of the participating parents and their children in our survey were quite similar to CDC’s 2016 NIS weighted sample estimates (Table 1). The most notable differences were that in our survey, respondents had a lower proportion of mothers with a high school or less formal education compared to the NIS (28% vs. 44%) and a lower proportion of households with incomes under $40,000 1 These reflect the frequency distribution arising from repeated application of the sampling algorithm from the frame (the mobile panel).
Ninety-six percent of respondents reported that all their children aged 19 to 35 months had received all vaccines recommended for children up to their age. However, more than one in five parents (22.1%) said they had delayed having their child/children getting a recommended vaccine for reasons other than illness or allergy. Moreover, 3.5% of all parents indicated they had decided not to have their child/children get a recommended vaccine. In addition, while seasonal flu vaccination is on the childhood vaccination schedule, there was far greater parent declination of this vaccine, which depending on the child’s age, involves one or two doses. Here, 65% of parents reported that their children aged 19 to 35 months had received a flu vaccination during the past year. Comparing the 96% of parents reporting their children received all recommended vaccines with the 65% reporting their children received the flu vaccines suggests that many parents in this survey were unaware the childhood immunization schedule included flu vaccination. Nearly 97% of parents said that they planned or intended to have their children get all the remaining recommended vaccines, while 3.3% say that they did not (Table 2). This proportion was substantially larger than the proportion who indicated intention to get the flu vaccine, which provided further evidence many parents did not realize that flu vaccine is included in the childhood vaccination schedule. The demographic factors most closely associated with immunization behaviors were respondents’ education level and selfreported household income. The percentage of parents reporting their children had received all recommended vaccinations increased with parental education from 94.5% to 97.8%, although the association was limited by the high base rate for all education levels. Along with parent education, parents’ household income was positively associated with children receiving all recommended vaccines, with vaccination delays and declination also declining as household income increased. In addition, non-Hispanic white parents were less likely to indicate delay or refusal of recommended childhood vaccines, compared to non-Hispanic black parents. However, non-Hispanic white parents were less likely to have their children get a flu vaccination than other racial/ethnic groups (Table 2). 3.3. Immunization-related beliefs Nine of ten parents agreed that childhood vaccines were effective (92%); that having their child vaccinated was important for the health of others in their community (93%); and that childhood vaccines were important for their child’s health (95%). Overall, a majority parents (75%) also agreed that the information they received about vaccines from the government was reliable and trustworthy (Table 3). At the same time, most parents also agreed that it was painful for children to receive so many shots (75%), with
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx
Table 1 Comparison of NIS and Panel Sample Characteristics. 2016 NIS (weighted) N = 27,455
2016 Panel Survey (unweighted) N = 1001
1.04
1.09
64.7 (0.5)
64.6 (1.5)
26.9 (0.5)
28.2 (1.4)
5.8 (0.3) 2.5 (0.2)
2.4 (0.5) 4.9 (0.7)
Age of children, % (SE) 19–23 months 24–29 months 30–35 months
30.3 (0.5) 33.9 (0.5) 35.8 (0.5)
32.0 (1.4) 42.9 (1.5) 25.1 (1.3)
Gender of children, % (SE) Male Female
51.2 (0.6) 48.8 (0.6)
51.9 (1.5) 48.1 (1.5)
Race of children, % (SE) White, non-Hispanic Black, non-Hispanic Hispanic Other/multiple race
46.3 13.3 26.6 13.8
(0.6) (0.4) (0.6) (0.4)
54.3 (1.5) 8.0 (0.8) 23.8 (1.3) 13.9 (1.0)
Census region, % (SE) Northeast Midwest South West
15.8 20.9 38.7 24.6
(0.3) (0.4) (0.5) (0.7)
15.2 21.4 36.4 27.0
Household income, % (SE) $0–20,000 $20,000–40,000 $40,000–75,000 >$75,000 Not sure/refused
22.5 18.3 18.0 30.7 10.5
(0.5) (0.5) (0.4) (0.5) (0.4)
13.0 (1.0) 21.9 (1.3) 31.6 (1.4) 28.2 (1.4) 5.3 (0.7)
Living arrangement, % (SE) Owned or being bought Renter Other arrangement
50.0 (0.6) 44.8 (0.6) 4.3 (0.3)
56.2 (1.5) 40.8 (1.5) 3.0 (0.5)
Number of eligible children in household (mean), n Respondent Relationship to child, % (SE) Mother (step, foster, adoptive) or female guardian Father (step, foster, adoptive) or male guardian Grandparent Other family member or friend
(1.1) (1.2) (1.5) (1.3)
Maternal education for the 1st child in household, % (SE) <12 years 14.5 (0.5) 12 years 25.6 (0.6) Some college 23.2 (0.5) College graduate 36.6 (0.5)
8.9 (0.9) 18.8 (1.2) 35.0 (1.5) 37.3 (1.5)
Maternal Age for the 1st child in household, % (SE) 29 years old 38.3 (0.6) 30 years old 61.7 (0.6)
45.2 (1.9)* 54.8 (1.9)*
SE, standard error. * For Panel Survey, only a subset of respondents have mother’s age available (N = 702).
just over half agreeing that children received too many vaccines in one doctor visit (54%). Nearly half agreed that children get too many vaccines during the first three years of life (45%) and that some vaccines were given to children to prevent diseases that they are unlikely to get (46%). In addition, about one third of parents believed that some vaccines are given to children to prevent diseases that are not serious (33%); some vaccines have ingredients that are unsafe (35%). A smaller portion believed that some vaccines may cause learning disabilities such as autism (19%). To identify and examine relationships between immunizationrelated beliefs and parent adherence with the overall schedule, we compared responses from parents reported not delaying or declining a recommended childhood vaccination with those who said they had. Overall, 3.5% of respondents reported having refused one or more vaccinations, while an additional 22.1% reported having delayed a recommended vaccination, leaving the remaining
74% of parents in the non-delay or refusal group. The analyses undertaken here revealed relatively large statistically significant differences on all eleven belief measures with respect to the three groups. As seen in Table 4, parents who had not delayed or declined recommended vaccinations for their children were most likely to believe that childhood vaccines were important for their child’s health, that childhood vaccines were effective, that having their child vaccinated was important for the health of others in their community, and that the information they received about vaccines from the government was reliable and trustworthy. In addition, far fewer of these parents believed that some vaccines may cause learning disabilities, contain unsafe ingredients, or that some vaccines are given to prevent diseases that are not serious. On some belief items, parents who delayed recommended childhood vaccines were closely aligned with parents who did not decline or delay vaccination, such as believing childhood vaccines are important for their child’s health, that childhood vaccines are effective, and that having their child vaccinated is important for the health of others in the community. However, parents who delayed vaccines were most likely to believe it was painful for children to receive so many shots during one doctor’s visit. In addition, for the other belief items, the responses of parents who had delayed vaccines were more similar to parents who reported declining recommended vaccines. Large percentages of delaying and declining parents believed children received too many vaccines in one doctor’s visit and during the first three years of life, that vaccines have ingredients that are unsafe, that vaccines are given to children to prevent diseases they are unlikely to get, and some vaccines are given to children to prevent diseases that are not serious. Notably, 48.7% of delaying parents and 58.1% of declining parents indicated some level of agreement with the statement vaccines may cause learning disabilities, including autism. While two-thirds of delaying parents said vaccine information from government was reliable and trustworthy, only 43.3% declining parents indicated agreement. The strongest correlation between parents’ self-reported childhood vaccination behaviors and vaccine beliefs was that some vaccines include ingredients that are unsafe (0.400). 3.4. Immunization-related beliefs in subpopulations As Table 5 indicates, we compared the eleven immunization beliefs by respondent’s education, household income and race/ethnicity. Positive beliefs (Beliefs 8–10) about the benefits of childhood vaccines tended to increase with parents’ education levels while agreement with statements about potential risks (Beliefs 1 – 7) of childhood vaccines tended to decline. Similarly, positive beliefs about the benefits of immunization tended to increase with household income, while beliefs about risks tended to decline. Notably, parents with some college or less formal education were most likely to believe some vaccines are given to children to prevent diseases that are not serious and were less likely to believe government information about vaccines was reliable and trustworthy. With respect to race/ethnicity, non-Hispanic white parents tended to have higher levels of agreement with statements involving the benefits of childhood vaccines than non-Hispanic black or Hispanic respondents, and lower levels of agreement with statements about the risks of childhood vaccines (Table 5). 4. Discussion Although the importance of parent understanding and behaviors in achieving childhood immunization goals have been long recognized, there is no ongoing surveillance in the U.S. of parent beliefs and intentions related to childhood immunization [1]. The
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx Table 2 Immunization Behaviors by Demographics: Percentage with behavior in each demographic grouping.
Total (Yes), % Education, % (SE) HS or less (N = 200) Some college (N = 403) College grad (N = 263) Post grad (N = 135)
Never Delayed or Declined Vaccine for Child1 N = 1001
Ever Delayed Vaccine for child(ren)2 N = 1001
Ever Not get vaccine for child(ren)3 N = 1001
Plan to get all vaccines for child(ren)4 N = 1001
Child(ren) had a flu vaccination N = 10015
96.1
22.1
3.5
96.7
65.1
94.5 95.8 97.0 97.8
(1.6) (1.0) (1.1) (1.3)
27.0 19.9 23.6 18.5
(3.1) (2.0) (2.6) (3.3)
5.0 4.0 2.7 1.5
(1.5) (1.0) (1.0) (1.0)
96.0 (1.4)* 95.3 (1.1)* 97.7 (0.9)* 100.0 (0.0)*
54.0% 62.0% 73.8% 74.1%
(3.5)* (2.4)* (2.7)* (3.8)*
Income, % (SE) <$35 k (N = 290) $35 k–49,999 (N = 198) $50 k–74,999 (N = 241) $75 k (N = 272)
95.2 95.5 95.9 97.8
(1.3) (1.5) (1.3) (0.9)
26.6 20.7 20.7 19.5
(2.6) (2.9) (2.6) (2.4)
4.1 5.1 3.3 1.8
(1.2) (1.6) (1.2) (0.8)
95.9 96.0 95.4 99.3
(1.2)* (1.4)* (1.3)* (0.5)*
60.7% 63.6% 68.5% 68.0%
(2.9) (3.4) (3.0) (2.8)
Ethnicity, % (SE) Non-Hispanic White (N = 652) Non-Hispanic Black (N = 98) Hispanic (N = 156) Other (N = 95)
95.7 96.9 96.2 97.9
(0.8) (1.7) (1.5) (1.5)
19.9 25.5 24.4 29.5
(1.6) (4.4) (3.4) (4.7)
2.9 5.1 3.8 5.3
(0.7) (2.2) (1.5) (2.3)
97.1 94.9 96.8 95.8
(0.7) (2.2) (1.4) (2.1)
62.4% 66.3% 66.7% 80.0%
(1.9)* (4.8)* (3.8)* (4.1)*
SE, standard error. * – Significant at 0.05, chi-square test for subgroup comparisons across all categories. 1 Question Text: (Has your child/have all of your children) received all of the vaccines that are recommend for children up to his/her age? 2 Question Text: Have you ever delayed having your child or children get a recommended vaccine for reasons other than illness or allergy? By delayed we mean put off, but ultimately ended up having it done. 3 Question Text: Have you ever decided not to have your child or children get a recommended vaccine for reasons other than illness or allergy? 4 Question Text: Do you plan or intend to have your child or children get all the remaining recommended vaccines? 5 Question Text: Since July 1, 2016 has {child} had a flu vaccination? There are two types of flu vaccinations. One is a shot and the other is a spray, mist, or drop in the nose.
Table 3 Immunization Beliefs: Percentage agreeing or disagreeing with each belief (N = 1001). Please indicate how much you agree or disagree with the following statement.
Agree strongly % (SE)
Agree somewhat % (SE)
Disagree somewhat % (SE)
Strongly disagree % (SE)
Not sure % (SE)
Belief 1: It is painful for children to receive so many shots during one doctor’s visit. Belief 2: Children receive too many vaccines in one doctor’s visit. Belief 3: Children get too many vaccines during the first three years of life. Belief 4: Vaccines may cause learning disabilities, such as autism. Belief 5: Some vaccines have ingredients that are unsafe. Belief 6: Some vaccines are given to children to prevent diseases they are not likely to get. Belief 7: Some vaccines are given to children to prevent diseases that are not serious. Belief 8: Childhood vaccines are important for my child’s health. Belief 9: Childhood vaccines are effective. Belief 10: Having my child vaccinated is important for the health of others in my community. Belief 11: The information I receive about vaccines from the government is reliable and trustworthy.
29.0 (1.4) 20.4 (1.3) 20.2 (1.3%) 8.0 (0.9) 11.2 (1.0) 16.5 (1.2) 11.6 (1.0) 71.9 (1.4) 63.9 (1.5) 72.8 (1.4) 33.4 (1.5)
46.3 33.2 24.4 11.3 23.3 29.8 20.9 22.8 28.6 19.9 41.1
15.8 (1.2) 30.4 (1.5) 27.7 (1.4) 16.8 (1.2) 23.8 (1.3) 24.8 (1.4) 26.8 (1.4) 2.9 (0.5) 3.5 (0.6) 3.2 (0.6) 11.5 (1.0)
7.5 (0.8) 13.3 (1.1) 25.2 (1.4) 47.1 (1.6) 20.7 (1.3) 23.1 (1.3) 35.1 (1.5) 1.7 (0.4) 1.5 (0.4) 2.5 (0.5) 5.0 (0.7)
1.4 (0.4) 2.7 (0.5) 2.5 (0.5) 16.8 (1.2) 21.0 (1.3) 5.8 (0.7) 5.6 (0.7) 0.7 (0.3) 2.5 (0.5) 1.6 (0.4) 9.0 (0.9)
NIS does not routinely include belief-related measures or questions in its annual assessments of childhood immunization rates. Moreover, the low population proportion of households with children of aged 19 to 35 months (less than 5%) makes the screening cost of traditional probability surveys prohibitively expensive. Consequently, the relatively few surveys concerning beliefs and intentions toward childhood immunization usually involve obtaining responses from all adults, or parents of children under 18, or more rarely children under age 6 [1]. Surveys of parents with children three years old and younger are infrequent and usually have samples too small to analyze differences between subpopulations. In order to assess the beliefs, intentions, and behaviors of parents of children at immunization age, differences in those beliefs between demographic subgroups, and the relation between immunization beliefs and behavior, we conducted a survey using a national non-probability panel, which allowed us to complete surveys with a national sample of 1001 eligible parents. The demographic characteristics of the parents and children in the survey sample obtained here were generally comparable to those of CDC’s NIS and as such, provided evidence that the panel’s composition
(1.6) (1.5) (1.4) (1.0) (1.3) (1.4) (1.3) (1.3) (1.4) (1.3) (1.6)
did not differ in either many or in substantial ways. The survey was conducted in less than one week in a cost-effective manner). Non-probability panels are widely recognized as substantially less expensive than traditional probability samples because they do not involve screening costs to identify households or eligible adults, do not require interviewers, do not require telephone, printing or mailing costs, and multiple attempts are virtually costless. Moreover, when the target characteristic is part of the panel profile, e.g., children in household, then screening costs are dramatically reduced. While the approach does not enable calculation of confidence intervals around survey responses, it can provide immunization programs and providers with the means to do relatively rapid assessments of parents’ beliefs and intentions regarding vaccines and/or the recommended childhood immunization schedule. Importantly, the survey approach used here was able to provide insights into the overall beliefs and behaviors of parents with children 19–35 months of age regarding childhood vaccination as well as find evidence of important differences in beliefs, particularly with respect to parents who reported having delayed or declined recommended childhood vaccinations. Parents who delayed or
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx
Table 4 Immunization Beliefs by Immunization Behavior: Total who agree (percent)4 with each belief for each behavior category. Please indicate how much you agree or disagree with the following statement.
N
Never Delayed or Declined Vaccine for Child1 %, (SE)
Ever Delayed Vaccine for child(ren)2 %, (SE)
Ever Not get vaccine for child(ren)3 %, (SE)
Belief 1: It is painful for children to receive so many shots during one doctor’s visit. Belief 2: Children receive too many vaccines in one doctor’s visit. Belief 3: Children get too many vaccines during the first three years of life. Belief 4: Vaccines may cause learning disabilities, such as autism. Belief 5: Some vaccines have ingredients that are unsafe. Belief 6: Some vaccines are given to children to prevent diseases they are not likely to get. Belief 7: Some vaccines are given to children to prevent diseases that are not serious. Belief 8: Childhood vaccines are important for my child’s health. Belief 9: Childhood vaccines are effective. Belief 10: Having my child vaccinated is important for the health of others in my community. Belief 11: The information I receive about vaccines from the government is reliable and trustworthy.
986
71.5 (1.7)
92.2 (1.8)
80.0 (6.8)
0.326*
973 975 832 790 942
45.9 36.1 13.6 32.4 42.7
81.4 73.1 48.7 71.4 66.5
79.4 73.5 58.1 75.8 73.5
(6.9) (7.6) (8.9) (7.5) (7.6)
0.378* 0.370* 0.357* 0.400* 0.283*
944
26.9 (1.7)
54.0 (3.4)
69.7 (8.0)
0.281*
994 976 985
98.2 (0.5) 97.9 (0.5) 97.0 (0.6)
90.0 (2.0) 88.6 (2.2) 90.2 (2.0)
68.6 (7.9) 68.6 (7.9) 58.8 (8.4)
0.245* 0.226* 0.239*
910
87.6 (1.3)
68.3 (3.3)
43.3 (9.1)
0.160*
(1.9) (1.8) (1.4) (2.0) (1.9)
(2.6) (3.0) (3.6) (3.3) (3.2)
Spearman Correlation5
SE, standard error. Missing data from belief question (Not Sure) excluded. * – Significant at 0.05. 1 – Respondent does not answer ‘Yes’ to either A1 or B2. 2 – A1: Have you ever delayed having your child or children get a recommended vaccine for reasons other than illness or allergy? By delayed we mean put off, but ultimately ended up having it done. 3 – B2: Have you ever decided not to have your child or children get a recommended vaccine for reasons other than illness or allergy? 4 – The total agree is defined as either respondent selected ‘‘Agree Strongly” or ‘‘Agree somewhat”. 5 – The Spearman correlations are between the 4-level attitude variables and the combined delay or decline group variable (respondent does not answer ‘Yes’ to either A1 or B2.)
refused a recommended immunization for their child were more likely to have concerns about the number of vaccines a child received during one doctor’s visit and during the first three years of life, both of which could be the basis for their delaying or refusing a recommended vaccination. Further, unlike parents who had never delayed or declined recommended childhood vaccines, a majority of parents who delayed or declined vaccines for their children believed some vaccines have ingredients that are unsafe, are given to prevent diseases children are not likely to get or are given to prevent diseases that are not serious. As such, these findings provide helpful insights into the knowledge deficits and beliefs that may be hindering parents’ compliance with the recommended childhood immunization schedule. The results here thus suggest immunization programs and providers need to be prepared to address questions and concerns related to vaccine ingredients, the timing of recommended vaccinations, and the potential harms posed by all vaccine preventable diseases. In addition, the associations found here between demographic characteristics and belief measures suggest immunization programs and providers should be mindful that parents with less formal education or household income also may be likely to have questions or doubts about the safety of vaccines as well as the importance of all recommended childhood vaccines, which can be hard to discern given many studies have focused on higher education and higher income parents [13,14]. In addition, this study may suggest using non-probability samples, including those involving smartphone panels, to assess the childhood vaccination-related beliefs, intentions, and behaviors of parents of young children. Given the often-considerable interest in vaccination confidence and hesitancy [1,15], it is important for immunization programs and providers to have survey research methods and approaches that enable fast, and if needed, welldefined samples to identify or monitor parents’ beliefs, intentions, and behaviors regarding childhood immunization. Since costs and resources likely preclude the routine use of probability samples for survey research focused on parents’ intentions and beliefs related
to childhood immunization at the community, state or national level, samples drawn from non-probability panels can provide a representative sample and be helpful in identifying and monitoring parental sentiments toward immunization as potential precursors of changes in immunization behaviors. The methodology used here illustrates that combining such samples with smartphone data collection can provide a relatively fast and lower-cost approach for identifying potential indicators or correlates of parental vaccination acceptance and compliance (e.g., the underlying beliefs that may be associated with increased delays or refusals). As such, the findings, in turn, can be used by public health agencies and immunization providers to inform their vaccination education and communication efforts and to guide decisions regarding additions to traditional probability-based survey research methods.
5. Limitations While non-probability panels can be designed to provide geographic and demographically representative samples, one of their limitations is that they are unlike probability-based samples from which we can make statistical projections to the broader population within known limits. Nonetheless, the correlation between immunization beliefs and education, income and parental race/ ethnicity in this survey demonstrates the importance of a demographically balanced sample to estimates of intent, beliefs and behaviors. However, it does not assure that other sources of bias have been minimized. In the U.S., 94% and 89% of the adults ages 18–29 and 30–49 own smartphones [5]. This is the predominant segment of the population with children in the targeted age range for this study. While this yields some coverage error due to the high levels of smartphone ownership in the combined age range, it is unlikely that the use of an app enabled survey will introduce a coverage error large enough to bias estimates. Another limitation is that the question ‘‘Did your child receive all recommended vaccines?” does not capture the complexities of
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx Table 5 Immunization Beliefs by Demographics: Total who agree (percent) with each belief in each demographic grouping1. Education HS or less
Income Some college
Race/Ethnicity
College grad
Post grad
<$35 k
$35–49 K
$50– 74 K
>$75 K
NH White
NH Black
Hispanic
Other
74.6 (2.7)
74.4 (3.8)
79.5 (2.4)
77.0 (3.0)
78.4 (2.7)
70.8 (2.8)
73.2* (1.7)
82.3* (3.9)
84.4* (2.9)
78.7* (4.2)
Belief 2: Too many vaccinations in one visit, % (SE) Total agree 61.1 (3.5) 56.0 (2.5) 52.9 (3.1)
48.1 (4.3)
58.5 (3.0)
55.2 (3.6)
58.7 (3.2)
48.3 (3.1)
51.4* (2.0)
58.3* (5.0)
63.9* (3.9)
62.4* (5.0)
Belief 3: Too many vaccinations in first 3 years, % (SE) Total agree 49.5 (3.6) 44.8 (2.5) 48.4 (3.1) 37.9 (4.2)
48.6 (3.0)
48.7 (3.6)
47.0 (3.3)
39.4 (3.0)
39.3* (1.9)
52.6* (5.1)
59.4* (3.9)
59.6* (5.1)
Belief 4: Vaccines may cause learning disabilities, % (SE) Total agree 27.9 (3.5) 24.1 (2.4) 21.4 (2.7) 17.6 (3.5)
28.1 (3.0)
24.7 (3.4)
23.0 (2.9)
17.5 (2.5)
20.1* (1.7)
39.4* (5.8)
27.2* (4.0)
24.4* (4.9)
Belief 5: Vaccines have unsafe ingredients, % (SE) Total agree 54.1* 45.0* (2.8) 39.5* (3.3) (4.1)
34.8* (4.4)
51.9* (3.5)
45.5* (4.0)
43.7* (3.5)
34.9* (3.2)
39.6* (2.1)
68.5* (5.4)
44.6* (4.5)
46.1* (5.7)
Belief 6: Vaccines prevent unlikely diseases, % (SE) Total agree 58.3* 53.6* (2.6) 45.6* (3.1) (3.6)
29.4* (4.1)
57.3* (3.0)
54.2* (3.6)
46.8* (3.3)
39.0* (3.1)
46.1* (2.0)
66.7* (5.0)
50.0* (4.1)
51.8* (5.5)
38.9* (3.0)
35.4* (3.5)
37.5* (3.2)
26.4* (2.7)
31.0* (1.9)
42.0* (5.3)
36.9* (4.0)
47.1* (5.4)
92.7* (1.5)
94.9* (1.6)
95.8* (1.3)
98.2* (0.8)
95.4 (0.8)
94.7 (2.3)
93.5(2.0)
98.9 (1.0)
92.4* (1.6)
93.2* (1.8)
95.8* (1.3)
97.8* (0.9)
95.3* (0.8)
88.9* (3.3)
94.7* (1.8)
97.8* (1.5)
91.8 (1.6)
93.4 (1.8)
95.4 (1.4)
96.3 (1.2)
94.6 (0.9)
90.5 (3.0)
93.4 (2.0)
96.8 (1.8)
77.3* (3.1)
84.5* (2.4)
87.6* (2.1)
82.7* (1.6)
72.7* (4.8)
77.6* (3.5)
92.1* (2.9)
Belief 1: Vaccination too painful, % (SE) Total agree 83.2 (2.7) 74.7 (2.2)
Belief 7: Vaccines prevent diseases that are not serious, % (SE) Total agree 38.6* 37.4* (2.5) 32.3* (2.9) 24.0* (3.6) (3.8) Belief 8: Vaccines important for my child’s health, % (SE) Total agree 93.4 (1.8) 95.3 (1.1) 95.4 (1.3) 98.5 (1.0) Belief 9: Vaccines are effective, % (SE) Total agree 93.2 (1.8) 94.1 (1.2)
95.7 (1.3)
97.8 (1.3)
Belief 10: Vaccines are important to others’ health, % (SE) Total agree 90.2* 94.5* (1.1) 94.6* (1.4) 98.5* (2.1) (1.1)
Belief 11: Government information on vaccines is trustworthy, % (SE) Total agree 72.0* 80.6* (2.1) 85.7* (2.2) 91.5* 77.1* (3.4) (2.5) (2.7) NH, non-Hispanic; SE, standard error. * – Significant at 0.05 level. 1 – the row N’s are the same as in Table 4.
the immunization schedule nor optimize respondents’ awareness and recall of the childhood immunization schedule. In addition to not being able to discern how well parents know the recommended schedule, a single general question does not fully reflect how well parents are complying with the schedule. Survey timing is another consideration and potential limitation. In using smartphone or other panel-based survey research methods, it may be important to purposively select the timing for field implementation to ensure that analyses do not under-report key outcomes, such as the proportion of flu vaccination coverage. We did not conduct analyses that looked at respondent age group differences or multivariate analyses including interaction effects. We will consider this for future work. Finally, while these results show promise for the use of non-probability panels and smartphone survey methods, this project was conducted as an initial proof of concept pilot study. Additional replications of this type of survey research are needed to provide additional insights into its reliability and validity for monitoring parents’ beliefs, intentions, and behaviors, including its value for tracking beliefs and intentions over time. In addition, replication with a traditional probability sample would provide evidence of the external validity of the findings relative to the general population of parents of young children.
6. Conclusion This study used a demographically and geographically representative non-probability smartphone consumer panel and a smartphone software app to assess the childhood immunizationrelated beliefs, intentions, and behaviors of parents with children 19–35 months old. This approach was able to obtain responses from 1001 parents over the course of a few days rather than months, and at a fraction of the cost of traditional probabilitybased survey research approaches. Non-probability panels are less expensive than probability samples as the lower costs are attributable to alleviating the effort associated with screening and interviewing. When using non-probability panels, confidence intervals cannot be calculated as in traditional probability samples. However, surveys can be conducted faster and can provide health departments and providers with a tool for rapid assessments of parents’ beliefs and intentions regarding vaccines and/or the recommended childhood immunization schedule. This approach also enables the attainment of sample sizes large enough to detect differences in population segments, such as lower income households or specific racial/ethnic sub-populations, where immunizationrelated beliefs and intentions may vary or be influenced by different factors (e.g., health information sources or access to health care
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx
resources). Although probability samples remain the gold standard for survey research, non-probability samples are increasingly accepted when factors such as a limited budget, high data collection costs, or urgency make it infeasible to use a probability sample. Funding source This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. CRediT authorship contribution statement John Boyle: Conceptualization, Methodology, Formal analysis, Investigation, Writing - original draft, Writing - review & editing, Supervision. Lew Berman: Conceptualization, Methodology, Investigation, Writing - original draft, Writing - review & editing. Glen Nowak: Conceptualization, Formal analysis, Writing - review & editing. Ronaldo Iachan: Methodology, Formal analysis, Investigation, Writing - review & editing. Deirdre Middleton: Methodology, Formal analysis, Investigation, Data curation, Writing - review & editing, Project administration. Yangyang Deng: Formal analysis, Data curation.
[2]
[3]
[4]
[5] [6] [7] [8]
[9]
[10]
[11]
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
[12]
[13]
Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.vaccine.2020.01.032.
[14] [15]
References
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[1] National Vaccine Advisory Committee. Assessing the state of vaccine confidence in the United States: recommendations from the national vaccine
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
Contents lists available at ScienceDirect
Vaccine journal homepage: www.elsevier.com/locate/vaccine
An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel John Boyle a, Lew Berman a, Glen J. Nowak b, Ronaldo Iachan a, Deirdre Middleton a,⇑, Yangyang Deng a a b
ICF, 530 Gaither Rd, Suite 500, Rockville, MD 20850, United States Grady College Center for Health & Risk Communication, 120 Hooper Street, University of Georgia, Athens, GA 30047, United States
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 7 December 2019 Accepted 9 January 2020 Available online xxxx Keywords: Survey research Nonprobability sampling Vaccine hesitancy Attitudes and beliefs
a b s t r a c t Introduction: It is important to quickly identify parent beliefs, intentions, and behaviors toward childhood vaccination, especially parents of children 19 to 35 months. This paper describes parental immunization beliefs, intentions, and behaviors; assesses the relationships between beliefs and intentions regarding child immunization and actual behaviors; and assesses whether beliefs, intentions, and/or behaviors varied across demographic subgroups. Methods: A sample of parents, ages 18 and older, from a mobile panel with people residing in the U.S. were invited to answer immunization behavior, intention, and belief questions using a smartphone app that was not vaccine specific. 10,000 panel members with a child under 18 were sent invitations. 1029 surveys were completed by a respondent with a child 19 to 35 months. The survey instrument replicated many NIS questions and had similar sequencing. Findings: Respondents reported that most children received all recommended vaccines, except flu vaccine, suggesting some may not understand the immunization schedule. Demographics closely associated with immunization behaviors were respondents’ education and household income. There is strong agreement that vaccines are effective, important to community health, and the child’s health. There is concern about the number of shots received, disease prevention, and ingredient safety. Some belief remains about vaccines causing learning disabilities. Positive beliefs about the benefits of childhood vaccines and concomitant risks vary with demographics. Conclusions: This survey provided insights into beliefs and behaviors of parents regarding childhood vaccination. It found evidence of differences in beliefs, particularly related to delaying or declining recommended childhood vaccinations. The survey was conducted in a few days and at lower cost than traditional methods. This serves as a model for health agencies where rapid results or inexpensive approaches are needed. Ó 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction Consistently high childhood immunization rates have greatly reduced the rates of death, disability, and illness from communicable diseases in the United States. However, recent U.S. outbreaks of childhood diseases related to unimmunized children have raised concerns about parental commitment to recommended immunization schedules [1]. Knowing parents’ beliefs and intentions regarding recommended childhood immunizations can help immunization programs and health care providers better address vaccination concerns and identify emerging issues, particularly if
⇑ Corresponding author at: 530 Gaither Road, Suite 500, Rockville, MD 20850, United States. E-mail address: [email protected] (D. Middleton).
valid and reliable data can be collected more regularly and costefficiently. The U.S. Centers for Disease Control and Prevention’s (CDC) National Immunization Survey (NIS) remains the national gold standard for measuring and tracking vaccination rates among children 19–35 months old on an annual basis. However, this survey does not involve regular assessment of parent beliefs or intentions regarding recommended immunizations. The NIS design obtains yearly immunization coverage for 60 geographic areas, fifty of these are states, one is the District of Columbia, and nine involve predefined local areas [2]. Study data are released at least a year after field work is completed. Thus, the NIS is not temporally or geographically sensitive to discover rapidly emerging immunization concerns or identifying beliefs that may be related to vaccination hesitancy. Moreover, since the population proportion of the target population – parents of children aged 19 to 35 months - is low (less
https://doi.org/10.1016/j.vaccine.2020.01.032 0264-410X/Ó 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx
than 5% of all U.S. households) and the sample size required to identify and assess behavior, intention, and belief differences in demographic subgroups is large, traditional telephone-based survey methods are very expensive for these assessments. It is thus important to identify and assess the value of other approaches, such as ones that involve geographically or demographically representative non-probability sampling frames. For example, the CDC has used non-probability samples since 2008 to assess immunization beliefs and behaviors related to seasonal flu vaccination among pregnant women and health care workers [3,4]. Over the last decade, the emergence of the Internet and the common use of mobile phones and more recently smartphones, has created new, and more rapid, capabilities for conducting survey research, particularly among individuals in the target population for early childhood vaccinations. Overall, the proportion of U.S. adults who own smartphones has grown from 35% in 2011 to 77% in 2018 [5]. Moreover, smartphone penetration exceeds 90% in the 18–49 year-old age cohort which contains almost all parents of children aged 19–35 months [5]. Smartphone software apps have been used to provide vaccine and vaccination schedule information to parents and to increase parents’ acceptance of MMR vaccine [6] and as part of mobile phone-based interventions to improve routine childhood immunization coverage, particularly in low- and middle-income countries [7,8]. A study in Canada used an immunization-related application to determine whether the use of a mobile immunization app was associated with the likelihood of reporting on-time vaccination in a cohort of 50 childbearing women [9]. The pervasive reach and use of smartphones open a potential pathway for research on childhood immunization beliefs, intentions, and behaviors that warrants consideration, particularly for more rapid or targeted assessments. Therefore, our research adopted this data collection strategy to address three central objectives: (1) describing parental immunization-related beliefs, intentions, and behaviors; (2) assessing the relationships between beliefs and intentions regarding child immunization and actual behaviors (i.e., refusals or delays in recommended vaccinations); and (3) assessing whether beliefs, intentions, and/or behaviors varied across various demographic subgroups. We believe this is the first study to use a smartphone panel and a software app to survey parents of children ages 19–35 months to quickly gain insights into their beliefs, intentions and behaviors towards recommended childhood vaccinations. 2. Research method A sample of parents, ages 18 and older, from the MFour allmobile consumer panel was invited to answer immunizationrelated behavior, intention, and belief questions. The survey was implemented between December 16 and 21, 2017, via the Surveys On The GoÒ mobile research app for Android or iOS smartphones. Those individuals who download the app, agree to the terms of service and create an account become panel members. The app allows panel members to receive invitations to surveys and to complete them in exchange for small financial incentives. On average, it took respondents 10 min to complete the survey. Respondents from all 50 states and the District of Columbia were represented in the final sample. This study and the processes within the study for the protection of human subjects were reviewed and approved by the ICF Institutional Review Board. 2.1. Sample selection The frame for this study was the MFour mobile panel, which was used to draw a non-probability sample of U.S. adults ages 18
and over with at least one child between the ages of 19 and 35 months old. At the time of the study, the MFour panel was comprised of approximately 2 million people. People in the full panel had to be age 13 and over, living in any of the 50 states, own a smartphone with Android or iOS, and have registered to receive and respond to survey opportunities using the Surveys On The GoÒ app. Individuals qualified for panel inclusion by completing a series of profiling questions and fraud detection measures. While the panel does not provide a comprehensive population frame or enable probability samples, for the general population, it is designed to provide national non-probability samples of adults that are geographically and demographically representative of the U.S. adult population. The sample drawn for this survey was large enough to detect differences in beliefs by sociodemographic characteristics and subpopulations, which is important for identifying potential differences in immunization-related beliefs, intentions, and behaviors across population segments. The MFour panel included members’ age, zip code, and whether there were children under 18 in the household. Thus, samples can be restricted to adults or specific geographic areas if desired. Importantly, the panel methodology enabled efficient targeting of a national sample of parents of children under 18 years old for the initial household screening. In this study, for instance, a national sample of 10,000 mobile panel members who were known to have a child under 18 years old in the household were sent the initial invitations to participate in the survey. Eligible adults who completed the survey earned one dollar for their participation. The amount of the reward for participation was included in the invitation but the purpose and subject matter was not. 2.2. Participant screening A total of 1029 surveys were completed by respondents who had a child aged 19 to 35 months old in their household. The survey program validated eligibility by requesting the month, day, and year of birth for each child reported. A software program calculated the actual age in months for each child, and only respondents who had an age-eligible child were invited to complete the rest of the survey. These eligible participants, in turn, were asked whether they were the person who knew the most about the health, doctor visits, and immunizations or shots that the target children had received. Almost all (97.3%) reported that they were the most knowledgeable. For purposes of comparability to the NIS, only the 1001 respondents who indicated they were the most knowledgeable adult in the household were included in the analyses. 2.3. Survey instrument The survey instrument replicated many survey questions as well as sequencing from the NIS in order to assess comparability of demographics and reported behaviors between the NIS and the panel sample. This included questions on the age of child, gender of child, race of child, respondent relationship to child, living arrangement, maternal education, and household income for direct comparisons to NIS estimates. However, we did not incorporate the NIS physician follow-up survey items as our study was focused on parental beliefs, intentions, and behaviors rather than verification of a child’s vaccination record. The survey also included questions related to respondents’ education and race/ethnicity, which along with household income, were used to identify and analyze demographic differences in parental immunization beliefs, intentions, and behavior rather than to conduct a comprehensive analysis of socio-economic health disparities. Childhood immunization behaviors were assessed using five measures. Two measures, received all recommended vaccines and flu vaccination in past year, were drawn from the NIS [10].
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
J. Boyle et al. / Vaccine xxx (xxxx) xxx
Two measures, delayed and refused childhood vaccines, were drawn from the six behavioral items in the Parental Attitudes and Childhood Vaccines (PACV) survey tool [11]. One item on future immunization intention was added. Seven immunizationrelated belief questions were drawn from 11 potential concerns assessed in the 2009 HealthStyles Survey of parents [12]. The seven items were nearly identical, but they were structured as four-point Likert scales in this survey. An additional three belief items - vaccines are effective, important for my child’s health, and important for the health of others in the community - were drawn from other questions in the same survey but used the same response categories as the other belief items in this study. A final belief question about the reliability and trustworthiness of information about vaccines from the government was added in the same format to complete the scale.
3
compared to the NIS (35% vs. 41%). In both surveys, the average number of eligible children in the household was one, with approximately half male (51% vs. 52%). In our survey, respondents’ eligible children were more likely to be 24–29 months of age and nonHispanic white compared to the NIS (46% vs. 30% and 54% vs. 46%, respectively). Given that smartphone ownership in the U.S. is substantially higher in persons under 50, there was a smaller percentage of grandparents in our survey (2.4%) compared to the NIS (5.8%). Post-stratification weights for sample estimates were not applied in the analysis since the study’s primary objectives were to examine correlations between parents’ childhood immunization beliefs and behaviors as well as differences in beliefs and behaviors among demographic subpopulations (vs. to generate total population estimates). 3.2. Self-reported children’s immunization status
2.4. Statistical analyses The analyses focused on the objectives described earlier: (1) describing respondents’ childhood immunization-related beliefs, intentions, and behaviors; (2) assessing the relationships between beliefs and intentions regarding child immunization and actual behaviors (i.e., refusals or delays in recommended vaccinations); and (3) assessing whether beliefs, intentions, and/or behaviors varied across various demographic subgroups. To address these goals, the analyses were primarily (1) examinations of associations and correlations and (2) bivariate analysis of these different measures and covariates. Associations were assessed using Pearson correlation coefficient and non-parametric Spearman (rank) correlation where more appropriate. While confidence intervals for the estimates are not presented given the use of a non-probability sample, standard errors were calculated and are provided to give a sense of the spread of distributions. We also used Chi-squared tests for categorical variables to identify significant differences across subgroups.1 All analyses were conducted with SPSS Statistics (IBM, Armonk, NY) and SAS version 9.4 (SAS Institute, Cary, NC). 3. Results The following sections summarize results from our analyses specifically related to comparisons between this sample and the NIS national probability sample, the immunization practices of this population including child vaccination status and intent, immunization beliefs and how these vary across key demographic groupings. 3.1. Comparisons to the national immunization survey After correcting for any known differences in selection probabilities (e.g., disproportionate sampling for geographic strata in the NIS), survey samples are typically compared to population parameters to determine whether additional post-stratification weighting is required to correct for demographic biases. We initially compared the characteristics of the respondents and children from our unweighted survey sample to the characteristics of the weighted NIS sample to identify potential bias. The demographic characteristics of the participating parents and their children in our survey were quite similar to CDC’s 2016 NIS weighted sample estimates (Table 1). The most notable differences were that in our survey, respondents had a lower proportion of mothers with a high school or less formal education compared to the NIS (28% vs. 44%) and a lower proportion of households with incomes under $40,000 1 These reflect the frequency distribution arising from repeated application of the sampling algorithm from the frame (the mobile panel).
Ninety-six percent of respondents reported that all their children aged 19 to 35 months had received all vaccines recommended for children up to their age. However, more than one in five parents (22.1%) said they had delayed having their child/children getting a recommended vaccine for reasons other than illness or allergy. Moreover, 3.5% of all parents indicated they had decided not to have their child/children get a recommended vaccine. In addition, while seasonal flu vaccination is on the childhood vaccination schedule, there was far greater parent declination of this vaccine, which depending on the child’s age, involves one or two doses. Here, 65% of parents reported that their children aged 19 to 35 months had received a flu vaccination during the past year. Comparing the 96% of parents reporting their children received all recommended vaccines with the 65% reporting their children received the flu vaccines suggests that many parents in this survey were unaware the childhood immunization schedule included flu vaccination. Nearly 97% of parents said that they planned or intended to have their children get all the remaining recommended vaccines, while 3.3% say that they did not (Table 2). This proportion was substantially larger than the proportion who indicated intention to get the flu vaccine, which provided further evidence many parents did not realize that flu vaccine is included in the childhood vaccination schedule. The demographic factors most closely associated with immunization behaviors were respondents’ education level and selfreported household income. The percentage of parents reporting their children had received all recommended vaccinations increased with parental education from 94.5% to 97.8%, although the association was limited by the high base rate for all education levels. Along with parent education, parents’ household income was positively associated with children receiving all recommended vaccines, with vaccination delays and declination also declining as household income increased. In addition, non-Hispanic white parents were less likely to indicate delay or refusal of recommended childhood vaccines, compared to non-Hispanic black parents. However, non-Hispanic white parents were less likely to have their children get a flu vaccination than other racial/ethnic groups (Table 2). 3.3. Immunization-related beliefs Nine of ten parents agreed that childhood vaccines were effective (92%); that having their child vaccinated was important for the health of others in their community (93%); and that childhood vaccines were important for their child’s health (95%). Overall, a majority parents (75%) also agreed that the information they received about vaccines from the government was reliable and trustworthy (Table 3). At the same time, most parents also agreed that it was painful for children to receive so many shots (75%), with
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
4
J. Boyle et al. / Vaccine xxx (xxxx) xxx
Table 1 Comparison of NIS and Panel Sample Characteristics. 2016 NIS (weighted) N = 27,455
2016 Panel Survey (unweighted) N = 1001
1.04
1.09
64.7 (0.5)
64.6 (1.5)
26.9 (0.5)
28.2 (1.4)
5.8 (0.3) 2.5 (0.2)
2.4 (0.5) 4.9 (0.7)
Age of children, % (SE) 19–23 months 24–29 months 30–35 months
30.3 (0.5) 33.9 (0.5) 35.8 (0.5)
32.0 (1.4) 42.9 (1.5) 25.1 (1.3)
Gender of children, % (SE) Male Female
51.2 (0.6) 48.8 (0.6)
51.9 (1.5) 48.1 (1.5)
Race of children, % (SE) White, non-Hispanic Black, non-Hispanic Hispanic Other/multiple race
46.3 13.3 26.6 13.8
(0.6) (0.4) (0.6) (0.4)
54.3 (1.5) 8.0 (0.8) 23.8 (1.3) 13.9 (1.0)
Census region, % (SE) Northeast Midwest South West
15.8 20.9 38.7 24.6
(0.3) (0.4) (0.5) (0.7)
15.2 21.4 36.4 27.0
Household income, % (SE) $0–20,000 $20,000–40,000 $40,000–75,000 >$75,000 Not sure/refused
22.5 18.3 18.0 30.7 10.5
(0.5) (0.5) (0.4) (0.5) (0.4)
13.0 (1.0) 21.9 (1.3) 31.6 (1.4) 28.2 (1.4) 5.3 (0.7)
Living arrangement, % (SE) Owned or being bought Renter Other arrangement
50.0 (0.6) 44.8 (0.6) 4.3 (0.3)
56.2 (1.5) 40.8 (1.5) 3.0 (0.5)
Number of eligible children in household (mean), n Respondent Relationship to child, % (SE) Mother (step, foster, adoptive) or female guardian Father (step, foster, adoptive) or male guardian Grandparent Other family member or friend
(1.1) (1.2) (1.5) (1.3)
Maternal education for the 1st child in household, % (SE) <12 years 14.5 (0.5) 12 years 25.6 (0.6) Some college 23.2 (0.5) College graduate 36.6 (0.5)
8.9 (0.9) 18.8 (1.2) 35.0 (1.5) 37.3 (1.5)
Maternal Age for the 1st child in household, % (SE) 29 years old 38.3 (0.6) 30 years old 61.7 (0.6)
45.2 (1.9)* 54.8 (1.9)*
SE, standard error. * For Panel Survey, only a subset of respondents have mother’s age available (N = 702).
just over half agreeing that children received too many vaccines in one doctor visit (54%). Nearly half agreed that children get too many vaccines during the first three years of life (45%) and that some vaccines were given to children to prevent diseases that they are unlikely to get (46%). In addition, about one third of parents believed that some vaccines are given to children to prevent diseases that are not serious (33%); some vaccines have ingredients that are unsafe (35%). A smaller portion believed that some vaccines may cause learning disabilities such as autism (19%). To identify and examine relationships between immunizationrelated beliefs and parent adherence with the overall schedule, we compared responses from parents reported not delaying or declining a recommended childhood vaccination with those who said they had. Overall, 3.5% of respondents reported having refused one or more vaccinations, while an additional 22.1% reported having delayed a recommended vaccination, leaving the remaining
74% of parents in the non-delay or refusal group. The analyses undertaken here revealed relatively large statistically significant differences on all eleven belief measures with respect to the three groups. As seen in Table 4, parents who had not delayed or declined recommended vaccinations for their children were most likely to believe that childhood vaccines were important for their child’s health, that childhood vaccines were effective, that having their child vaccinated was important for the health of others in their community, and that the information they received about vaccines from the government was reliable and trustworthy. In addition, far fewer of these parents believed that some vaccines may cause learning disabilities, contain unsafe ingredients, or that some vaccines are given to prevent diseases that are not serious. On some belief items, parents who delayed recommended childhood vaccines were closely aligned with parents who did not decline or delay vaccination, such as believing childhood vaccines are important for their child’s health, that childhood vaccines are effective, and that having their child vaccinated is important for the health of others in the community. However, parents who delayed vaccines were most likely to believe it was painful for children to receive so many shots during one doctor’s visit. In addition, for the other belief items, the responses of parents who had delayed vaccines were more similar to parents who reported declining recommended vaccines. Large percentages of delaying and declining parents believed children received too many vaccines in one doctor’s visit and during the first three years of life, that vaccines have ingredients that are unsafe, that vaccines are given to children to prevent diseases they are unlikely to get, and some vaccines are given to children to prevent diseases that are not serious. Notably, 48.7% of delaying parents and 58.1% of declining parents indicated some level of agreement with the statement vaccines may cause learning disabilities, including autism. While two-thirds of delaying parents said vaccine information from government was reliable and trustworthy, only 43.3% declining parents indicated agreement. The strongest correlation between parents’ self-reported childhood vaccination behaviors and vaccine beliefs was that some vaccines include ingredients that are unsafe (0.400). 3.4. Immunization-related beliefs in subpopulations As Table 5 indicates, we compared the eleven immunization beliefs by respondent’s education, household income and race/ethnicity. Positive beliefs (Beliefs 8–10) about the benefits of childhood vaccines tended to increase with parents’ education levels while agreement with statements about potential risks (Beliefs 1 – 7) of childhood vaccines tended to decline. Similarly, positive beliefs about the benefits of immunization tended to increase with household income, while beliefs about risks tended to decline. Notably, parents with some college or less formal education were most likely to believe some vaccines are given to children to prevent diseases that are not serious and were less likely to believe government information about vaccines was reliable and trustworthy. With respect to race/ethnicity, non-Hispanic white parents tended to have higher levels of agreement with statements involving the benefits of childhood vaccines than non-Hispanic black or Hispanic respondents, and lower levels of agreement with statements about the risks of childhood vaccines (Table 5). 4. Discussion Although the importance of parent understanding and behaviors in achieving childhood immunization goals have been long recognized, there is no ongoing surveillance in the U.S. of parent beliefs and intentions related to childhood immunization [1]. The
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
5
J. Boyle et al. / Vaccine xxx (xxxx) xxx Table 2 Immunization Behaviors by Demographics: Percentage with behavior in each demographic grouping.
Total (Yes), % Education, % (SE) HS or less (N = 200) Some college (N = 403) College grad (N = 263) Post grad (N = 135)
Never Delayed or Declined Vaccine for Child1 N = 1001
Ever Delayed Vaccine for child(ren)2 N = 1001
Ever Not get vaccine for child(ren)3 N = 1001
Plan to get all vaccines for child(ren)4 N = 1001
Child(ren) had a flu vaccination N = 10015
96.1
22.1
3.5
96.7
65.1
94.5 95.8 97.0 97.8
(1.6) (1.0) (1.1) (1.3)
27.0 19.9 23.6 18.5
(3.1) (2.0) (2.6) (3.3)
5.0 4.0 2.7 1.5
(1.5) (1.0) (1.0) (1.0)
96.0 (1.4)* 95.3 (1.1)* 97.7 (0.9)* 100.0 (0.0)*
54.0% 62.0% 73.8% 74.1%
(3.5)* (2.4)* (2.7)* (3.8)*
Income, % (SE) <$35 k (N = 290) $35 k–49,999 (N = 198) $50 k–74,999 (N = 241) $75 k (N = 272)
95.2 95.5 95.9 97.8
(1.3) (1.5) (1.3) (0.9)
26.6 20.7 20.7 19.5
(2.6) (2.9) (2.6) (2.4)
4.1 5.1 3.3 1.8
(1.2) (1.6) (1.2) (0.8)
95.9 96.0 95.4 99.3
(1.2)* (1.4)* (1.3)* (0.5)*
60.7% 63.6% 68.5% 68.0%
(2.9) (3.4) (3.0) (2.8)
Ethnicity, % (SE) Non-Hispanic White (N = 652) Non-Hispanic Black (N = 98) Hispanic (N = 156) Other (N = 95)
95.7 96.9 96.2 97.9
(0.8) (1.7) (1.5) (1.5)
19.9 25.5 24.4 29.5
(1.6) (4.4) (3.4) (4.7)
2.9 5.1 3.8 5.3
(0.7) (2.2) (1.5) (2.3)
97.1 94.9 96.8 95.8
(0.7) (2.2) (1.4) (2.1)
62.4% 66.3% 66.7% 80.0%
(1.9)* (4.8)* (3.8)* (4.1)*
SE, standard error. * – Significant at 0.05, chi-square test for subgroup comparisons across all categories. 1 Question Text: (Has your child/have all of your children) received all of the vaccines that are recommend for children up to his/her age? 2 Question Text: Have you ever delayed having your child or children get a recommended vaccine for reasons other than illness or allergy? By delayed we mean put off, but ultimately ended up having it done. 3 Question Text: Have you ever decided not to have your child or children get a recommended vaccine for reasons other than illness or allergy? 4 Question Text: Do you plan or intend to have your child or children get all the remaining recommended vaccines? 5 Question Text: Since July 1, 2016 has {child} had a flu vaccination? There are two types of flu vaccinations. One is a shot and the other is a spray, mist, or drop in the nose.
Table 3 Immunization Beliefs: Percentage agreeing or disagreeing with each belief (N = 1001). Please indicate how much you agree or disagree with the following statement.
Agree strongly % (SE)
Agree somewhat % (SE)
Disagree somewhat % (SE)
Strongly disagree % (SE)
Not sure % (SE)
Belief 1: It is painful for children to receive so many shots during one doctor’s visit. Belief 2: Children receive too many vaccines in one doctor’s visit. Belief 3: Children get too many vaccines during the first three years of life. Belief 4: Vaccines may cause learning disabilities, such as autism. Belief 5: Some vaccines have ingredients that are unsafe. Belief 6: Some vaccines are given to children to prevent diseases they are not likely to get. Belief 7: Some vaccines are given to children to prevent diseases that are not serious. Belief 8: Childhood vaccines are important for my child’s health. Belief 9: Childhood vaccines are effective. Belief 10: Having my child vaccinated is important for the health of others in my community. Belief 11: The information I receive about vaccines from the government is reliable and trustworthy.
29.0 (1.4) 20.4 (1.3) 20.2 (1.3%) 8.0 (0.9) 11.2 (1.0) 16.5 (1.2) 11.6 (1.0) 71.9 (1.4) 63.9 (1.5) 72.8 (1.4) 33.4 (1.5)
46.3 33.2 24.4 11.3 23.3 29.8 20.9 22.8 28.6 19.9 41.1
15.8 (1.2) 30.4 (1.5) 27.7 (1.4) 16.8 (1.2) 23.8 (1.3) 24.8 (1.4) 26.8 (1.4) 2.9 (0.5) 3.5 (0.6) 3.2 (0.6) 11.5 (1.0)
7.5 (0.8) 13.3 (1.1) 25.2 (1.4) 47.1 (1.6) 20.7 (1.3) 23.1 (1.3) 35.1 (1.5) 1.7 (0.4) 1.5 (0.4) 2.5 (0.5) 5.0 (0.7)
1.4 (0.4) 2.7 (0.5) 2.5 (0.5) 16.8 (1.2) 21.0 (1.3) 5.8 (0.7) 5.6 (0.7) 0.7 (0.3) 2.5 (0.5) 1.6 (0.4) 9.0 (0.9)
NIS does not routinely include belief-related measures or questions in its annual assessments of childhood immunization rates. Moreover, the low population proportion of households with children of aged 19 to 35 months (less than 5%) makes the screening cost of traditional probability surveys prohibitively expensive. Consequently, the relatively few surveys concerning beliefs and intentions toward childhood immunization usually involve obtaining responses from all adults, or parents of children under 18, or more rarely children under age 6 [1]. Surveys of parents with children three years old and younger are infrequent and usually have samples too small to analyze differences between subpopulations. In order to assess the beliefs, intentions, and behaviors of parents of children at immunization age, differences in those beliefs between demographic subgroups, and the relation between immunization beliefs and behavior, we conducted a survey using a national non-probability panel, which allowed us to complete surveys with a national sample of 1001 eligible parents. The demographic characteristics of the parents and children in the survey sample obtained here were generally comparable to those of CDC’s NIS and as such, provided evidence that the panel’s composition
(1.6) (1.5) (1.4) (1.0) (1.3) (1.4) (1.3) (1.3) (1.4) (1.3) (1.6)
did not differ in either many or in substantial ways. The survey was conducted in less than one week in a cost-effective manner). Non-probability panels are widely recognized as substantially less expensive than traditional probability samples because they do not involve screening costs to identify households or eligible adults, do not require interviewers, do not require telephone, printing or mailing costs, and multiple attempts are virtually costless. Moreover, when the target characteristic is part of the panel profile, e.g., children in household, then screening costs are dramatically reduced. While the approach does not enable calculation of confidence intervals around survey responses, it can provide immunization programs and providers with the means to do relatively rapid assessments of parents’ beliefs and intentions regarding vaccines and/or the recommended childhood immunization schedule. Importantly, the survey approach used here was able to provide insights into the overall beliefs and behaviors of parents with children 19–35 months of age regarding childhood vaccination as well as find evidence of important differences in beliefs, particularly with respect to parents who reported having delayed or declined recommended childhood vaccinations. Parents who delayed or
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
6
J. Boyle et al. / Vaccine xxx (xxxx) xxx
Table 4 Immunization Beliefs by Immunization Behavior: Total who agree (percent)4 with each belief for each behavior category. Please indicate how much you agree or disagree with the following statement.
N
Never Delayed or Declined Vaccine for Child1 %, (SE)
Ever Delayed Vaccine for child(ren)2 %, (SE)
Ever Not get vaccine for child(ren)3 %, (SE)
Belief 1: It is painful for children to receive so many shots during one doctor’s visit. Belief 2: Children receive too many vaccines in one doctor’s visit. Belief 3: Children get too many vaccines during the first three years of life. Belief 4: Vaccines may cause learning disabilities, such as autism. Belief 5: Some vaccines have ingredients that are unsafe. Belief 6: Some vaccines are given to children to prevent diseases they are not likely to get. Belief 7: Some vaccines are given to children to prevent diseases that are not serious. Belief 8: Childhood vaccines are important for my child’s health. Belief 9: Childhood vaccines are effective. Belief 10: Having my child vaccinated is important for the health of others in my community. Belief 11: The information I receive about vaccines from the government is reliable and trustworthy.
986
71.5 (1.7)
92.2 (1.8)
80.0 (6.8)
0.326*
973 975 832 790 942
45.9 36.1 13.6 32.4 42.7
81.4 73.1 48.7 71.4 66.5
79.4 73.5 58.1 75.8 73.5
(6.9) (7.6) (8.9) (7.5) (7.6)
0.378* 0.370* 0.357* 0.400* 0.283*
944
26.9 (1.7)
54.0 (3.4)
69.7 (8.0)
0.281*
994 976 985
98.2 (0.5) 97.9 (0.5) 97.0 (0.6)
90.0 (2.0) 88.6 (2.2) 90.2 (2.0)
68.6 (7.9) 68.6 (7.9) 58.8 (8.4)
0.245* 0.226* 0.239*
910
87.6 (1.3)
68.3 (3.3)
43.3 (9.1)
0.160*
(1.9) (1.8) (1.4) (2.0) (1.9)
(2.6) (3.0) (3.6) (3.3) (3.2)
Spearman Correlation5
SE, standard error. Missing data from belief question (Not Sure) excluded. * – Significant at 0.05. 1 – Respondent does not answer ‘Yes’ to either A1 or B2. 2 – A1: Have you ever delayed having your child or children get a recommended vaccine for reasons other than illness or allergy? By delayed we mean put off, but ultimately ended up having it done. 3 – B2: Have you ever decided not to have your child or children get a recommended vaccine for reasons other than illness or allergy? 4 – The total agree is defined as either respondent selected ‘‘Agree Strongly” or ‘‘Agree somewhat”. 5 – The Spearman correlations are between the 4-level attitude variables and the combined delay or decline group variable (respondent does not answer ‘Yes’ to either A1 or B2.)
refused a recommended immunization for their child were more likely to have concerns about the number of vaccines a child received during one doctor’s visit and during the first three years of life, both of which could be the basis for their delaying or refusing a recommended vaccination. Further, unlike parents who had never delayed or declined recommended childhood vaccines, a majority of parents who delayed or declined vaccines for their children believed some vaccines have ingredients that are unsafe, are given to prevent diseases children are not likely to get or are given to prevent diseases that are not serious. As such, these findings provide helpful insights into the knowledge deficits and beliefs that may be hindering parents’ compliance with the recommended childhood immunization schedule. The results here thus suggest immunization programs and providers need to be prepared to address questions and concerns related to vaccine ingredients, the timing of recommended vaccinations, and the potential harms posed by all vaccine preventable diseases. In addition, the associations found here between demographic characteristics and belief measures suggest immunization programs and providers should be mindful that parents with less formal education or household income also may be likely to have questions or doubts about the safety of vaccines as well as the importance of all recommended childhood vaccines, which can be hard to discern given many studies have focused on higher education and higher income parents [13,14]. In addition, this study may suggest using non-probability samples, including those involving smartphone panels, to assess the childhood vaccination-related beliefs, intentions, and behaviors of parents of young children. Given the often-considerable interest in vaccination confidence and hesitancy [1,15], it is important for immunization programs and providers to have survey research methods and approaches that enable fast, and if needed, welldefined samples to identify or monitor parents’ beliefs, intentions, and behaviors regarding childhood immunization. Since costs and resources likely preclude the routine use of probability samples for survey research focused on parents’ intentions and beliefs related
to childhood immunization at the community, state or national level, samples drawn from non-probability panels can provide a representative sample and be helpful in identifying and monitoring parental sentiments toward immunization as potential precursors of changes in immunization behaviors. The methodology used here illustrates that combining such samples with smartphone data collection can provide a relatively fast and lower-cost approach for identifying potential indicators or correlates of parental vaccination acceptance and compliance (e.g., the underlying beliefs that may be associated with increased delays or refusals). As such, the findings, in turn, can be used by public health agencies and immunization providers to inform their vaccination education and communication efforts and to guide decisions regarding additions to traditional probability-based survey research methods.
5. Limitations While non-probability panels can be designed to provide geographic and demographically representative samples, one of their limitations is that they are unlike probability-based samples from which we can make statistical projections to the broader population within known limits. Nonetheless, the correlation between immunization beliefs and education, income and parental race/ ethnicity in this survey demonstrates the importance of a demographically balanced sample to estimates of intent, beliefs and behaviors. However, it does not assure that other sources of bias have been minimized. In the U.S., 94% and 89% of the adults ages 18–29 and 30–49 own smartphones [5]. This is the predominant segment of the population with children in the targeted age range for this study. While this yields some coverage error due to the high levels of smartphone ownership in the combined age range, it is unlikely that the use of an app enabled survey will introduce a coverage error large enough to bias estimates. Another limitation is that the question ‘‘Did your child receive all recommended vaccines?” does not capture the complexities of
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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J. Boyle et al. / Vaccine xxx (xxxx) xxx Table 5 Immunization Beliefs by Demographics: Total who agree (percent) with each belief in each demographic grouping1. Education HS or less
Income Some college
Race/Ethnicity
College grad
Post grad
<$35 k
$35–49 K
$50– 74 K
>$75 K
NH White
NH Black
Hispanic
Other
74.6 (2.7)
74.4 (3.8)
79.5 (2.4)
77.0 (3.0)
78.4 (2.7)
70.8 (2.8)
73.2* (1.7)
82.3* (3.9)
84.4* (2.9)
78.7* (4.2)
Belief 2: Too many vaccinations in one visit, % (SE) Total agree 61.1 (3.5) 56.0 (2.5) 52.9 (3.1)
48.1 (4.3)
58.5 (3.0)
55.2 (3.6)
58.7 (3.2)
48.3 (3.1)
51.4* (2.0)
58.3* (5.0)
63.9* (3.9)
62.4* (5.0)
Belief 3: Too many vaccinations in first 3 years, % (SE) Total agree 49.5 (3.6) 44.8 (2.5) 48.4 (3.1) 37.9 (4.2)
48.6 (3.0)
48.7 (3.6)
47.0 (3.3)
39.4 (3.0)
39.3* (1.9)
52.6* (5.1)
59.4* (3.9)
59.6* (5.1)
Belief 4: Vaccines may cause learning disabilities, % (SE) Total agree 27.9 (3.5) 24.1 (2.4) 21.4 (2.7) 17.6 (3.5)
28.1 (3.0)
24.7 (3.4)
23.0 (2.9)
17.5 (2.5)
20.1* (1.7)
39.4* (5.8)
27.2* (4.0)
24.4* (4.9)
Belief 5: Vaccines have unsafe ingredients, % (SE) Total agree 54.1* 45.0* (2.8) 39.5* (3.3) (4.1)
34.8* (4.4)
51.9* (3.5)
45.5* (4.0)
43.7* (3.5)
34.9* (3.2)
39.6* (2.1)
68.5* (5.4)
44.6* (4.5)
46.1* (5.7)
Belief 6: Vaccines prevent unlikely diseases, % (SE) Total agree 58.3* 53.6* (2.6) 45.6* (3.1) (3.6)
29.4* (4.1)
57.3* (3.0)
54.2* (3.6)
46.8* (3.3)
39.0* (3.1)
46.1* (2.0)
66.7* (5.0)
50.0* (4.1)
51.8* (5.5)
38.9* (3.0)
35.4* (3.5)
37.5* (3.2)
26.4* (2.7)
31.0* (1.9)
42.0* (5.3)
36.9* (4.0)
47.1* (5.4)
92.7* (1.5)
94.9* (1.6)
95.8* (1.3)
98.2* (0.8)
95.4 (0.8)
94.7 (2.3)
93.5(2.0)
98.9 (1.0)
92.4* (1.6)
93.2* (1.8)
95.8* (1.3)
97.8* (0.9)
95.3* (0.8)
88.9* (3.3)
94.7* (1.8)
97.8* (1.5)
91.8 (1.6)
93.4 (1.8)
95.4 (1.4)
96.3 (1.2)
94.6 (0.9)
90.5 (3.0)
93.4 (2.0)
96.8 (1.8)
77.3* (3.1)
84.5* (2.4)
87.6* (2.1)
82.7* (1.6)
72.7* (4.8)
77.6* (3.5)
92.1* (2.9)
Belief 1: Vaccination too painful, % (SE) Total agree 83.2 (2.7) 74.7 (2.2)
Belief 7: Vaccines prevent diseases that are not serious, % (SE) Total agree 38.6* 37.4* (2.5) 32.3* (2.9) 24.0* (3.6) (3.8) Belief 8: Vaccines important for my child’s health, % (SE) Total agree 93.4 (1.8) 95.3 (1.1) 95.4 (1.3) 98.5 (1.0) Belief 9: Vaccines are effective, % (SE) Total agree 93.2 (1.8) 94.1 (1.2)
95.7 (1.3)
97.8 (1.3)
Belief 10: Vaccines are important to others’ health, % (SE) Total agree 90.2* 94.5* (1.1) 94.6* (1.4) 98.5* (2.1) (1.1)
Belief 11: Government information on vaccines is trustworthy, % (SE) Total agree 72.0* 80.6* (2.1) 85.7* (2.2) 91.5* 77.1* (3.4) (2.5) (2.7) NH, non-Hispanic; SE, standard error. * – Significant at 0.05 level. 1 – the row N’s are the same as in Table 4.
the immunization schedule nor optimize respondents’ awareness and recall of the childhood immunization schedule. In addition to not being able to discern how well parents know the recommended schedule, a single general question does not fully reflect how well parents are complying with the schedule. Survey timing is another consideration and potential limitation. In using smartphone or other panel-based survey research methods, it may be important to purposively select the timing for field implementation to ensure that analyses do not under-report key outcomes, such as the proportion of flu vaccination coverage. We did not conduct analyses that looked at respondent age group differences or multivariate analyses including interaction effects. We will consider this for future work. Finally, while these results show promise for the use of non-probability panels and smartphone survey methods, this project was conducted as an initial proof of concept pilot study. Additional replications of this type of survey research are needed to provide additional insights into its reliability and validity for monitoring parents’ beliefs, intentions, and behaviors, including its value for tracking beliefs and intentions over time. In addition, replication with a traditional probability sample would provide evidence of the external validity of the findings relative to the general population of parents of young children.
6. Conclusion This study used a demographically and geographically representative non-probability smartphone consumer panel and a smartphone software app to assess the childhood immunizationrelated beliefs, intentions, and behaviors of parents with children 19–35 months old. This approach was able to obtain responses from 1001 parents over the course of a few days rather than months, and at a fraction of the cost of traditional probabilitybased survey research approaches. Non-probability panels are less expensive than probability samples as the lower costs are attributable to alleviating the effort associated with screening and interviewing. When using non-probability panels, confidence intervals cannot be calculated as in traditional probability samples. However, surveys can be conducted faster and can provide health departments and providers with a tool for rapid assessments of parents’ beliefs and intentions regarding vaccines and/or the recommended childhood immunization schedule. This approach also enables the attainment of sample sizes large enough to detect differences in population segments, such as lower income households or specific racial/ethnic sub-populations, where immunizationrelated beliefs and intentions may vary or be influenced by different factors (e.g., health information sources or access to health care
Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032
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resources). Although probability samples remain the gold standard for survey research, non-probability samples are increasingly accepted when factors such as a limited budget, high data collection costs, or urgency make it infeasible to use a probability sample. Funding source This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. CRediT authorship contribution statement John Boyle: Conceptualization, Methodology, Formal analysis, Investigation, Writing - original draft, Writing - review & editing, Supervision. Lew Berman: Conceptualization, Methodology, Investigation, Writing - original draft, Writing - review & editing. Glen Nowak: Conceptualization, Formal analysis, Writing - review & editing. Ronaldo Iachan: Methodology, Formal analysis, Investigation, Writing - review & editing. Deirdre Middleton: Methodology, Formal analysis, Investigation, Data curation, Writing - review & editing, Project administration. Yangyang Deng: Formal analysis, Data curation.
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Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.vaccine.2020.01.032.
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Please cite this article as: J. Boyle, L. Berman, G. J. Nowak et al., An assessment of parents’ childhood immunization beliefs, intentions, and behaviors using a smartphone panel, Vaccine, https://doi.org/10.1016/j.vaccine.2020.01.032