Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018

Vaccine xxx (xxxx) xxx

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Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018 Chelsea S. Lutz a,b,c,⇑,1, Rebecca V. Fink d,e,2, Ann J. Cloud e, John Stevenson c,3, David Kim c,f,3, Amy Parker Fiebelkorn c a

Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, MD, United States Oak Ridge Institute for Science and Education, United States Department of Energy, Washington, DC, United States Immunization Services Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States d Westat, Rockville, MD, United States e Abt Associates, Cambridge, MA, United States f Division of Vaccines, Office of Infectious Disease and HIV/AIDS, Office of Assistant Secretary for Health, US Department of Health and Human Services, Washington, DC, United States b c

a r t i c l e

i n f o

Article history: Received 17 April 2019 Received in revised form 16 September 2019 Accepted 3 December 2019 Available online xxxx Keywords: Adult vaccination Influenza Influenza vaccination Vaccine perceptions Vaccine safety Vaccine effectiveness

a b s t r a c t Background: Annual vaccination against seasonal influenza is widely recognized as the primary intervention method in preventing morbidity and mortality from influenza, but coverage among adults is suboptimal in the United States. Safety and effectiveness perceptions regarding vaccines are consistently cited as factors that influence adults’ decisions to accept or reject vaccination. Therefore, we conducted this analysis in order to understand sociodemographic, attitude, and knowledge factors associated with these perceptions for influenza vaccine among adults in three different age groups. Methods: Probability-based Internet panel surveys using nationally representative samples of adults aged 19 years in the United States were conducted during February–March of 2017 and 2018. We asked respondents if they believed the influenza vaccine was safe and effective. We calculated prevalence ratios using chi-square and pairwise t-tests to determine associations between safety and effectiveness beliefs and sociodemographic variables for adults aged 19–49, 50–64, and 65 years. Results: Survey completion rates were 58.2% (2017) and 57.2% (2018); we analyzed 4597 combined responses. Overall, most adults reported the influenza vaccine was safe (86.3%) and effective (73.0%). However, fewer younger adults reported positive perceptions compared with older age groups. Respondents who believed the vaccine was safe also reported it was effective. Conclusions: Generally, adults perceived the influenza vaccine as safe and effective. Considering this, any improvements to these perceptions would likely be minor and have a limited effect on coverage. Future research to understand why, despite positive perceptions, adults are still choosing to forego the vaccine may be informative. Ó 2019 Elsevier Ltd. All rights reserved.

1. Introduction Annual influenza epidemics typically occur in the United States during the late fall through early spring, and can result in significant clinical and economic burdens, especially among older adults ⇑ Corresponding author. E-mail addresses: [email protected], [email protected] (C.S. Lutz), RebeccaV_Fink@ abtassoc.com (R.V. Fink), [email protected] (A.J. Cloud), [email protected] (D. Kim), [email protected] (A.P. Fiebelkorn). 1 AAffiliation A = current and primary affiliation; B and C=affiliations under which all work was conducted, no longer affiliated. 2 Affiliation E = affiliation under which all work was conducted, no longer affiliated. 3 Affiliation C = affiliation under which all work was conducted, since retired/no longer affiliated.

[1–3]. Annual vaccination against seasonal influenza is widely recognized as the primary intervention method in preventing morbidity and mortality from influenza [4]. Since 2010, the Advisory Committee on Immunization Practices has recommended that everyone six months of age and older receive an annual influenza vaccine [5]. However, adult influenza vaccination coverage is consistently below 45% and varies considerably by age group [6]. Coverage estimates for the 2016–17 season demonstrate that influenza vaccination rates among adults aged  65 years (65.3%) were markedly higher than among those aged 18–49 (33.6%) and 50–64 (45.4%) years [7]. Estimates for the 2017–18 season were lower overall, but followed a similar pattern: adults aged  65 years (59.6%)

https://doi.org/10.1016/j.vaccine.2019.12.004 0264-410X/Ó 2019 Elsevier Ltd. All rights reserved.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx

had the highest coverage rates compared with those aged 18–49 (26.9%) and 50–64 (39.7%) years [8]. In addition to differences observed among age groups, disparities in influenza vaccine coverage often exist among adults of different race/ethnicities, income and education levels, and insurance status [7–11]. Furthermore, perceptions regarding the influenza vaccine’s safety and effectiveness are consistently cited by adult patients as factors that impact their decision to accept or deny the vaccine [9,11–17]. What is not clear, however, is the effect these sociodemographic factors may have on safety and effectiveness perceptions, especially among different age groups, in which certain sociodemographic differences may be more pronounced. For example, according to the U.S. Census Bureau Current Population Survey, a greater proportion of adults aged 18–49 years old compared with adults aged  65 years reported having at least some college education [18]. Therefore, we evaluated sociodemographic factors associated with perceptions of influenza vaccine safety and effectiveness among adults in three age groups. 2. Methods 2.1. Survey samples Our analysis used data from a larger survey that evaluated implementation of components of the Standards for Adult Immunization Practice (i.e., vaccine assessment, recommendation, and vaccine offer and/or referral) at the respondent’s most recent visit to a healthcare provider within the past year, and survey questions used in our analysis were not the primary focus of the broader survey. This survey invited adults aged  19 years to participate using GfK’s KnowledgePanelÒ probability-based national Internet panel [19] and was administered annually during February–March from 2015 to 2018. Sociodemographic data for all panelists, including non-respondents, were already available for the sample. The survey oversampled self-reported Hispanics and non-Hispanic blacks to ensure comparable numbers of responses to non-Hispanic whites for analysis. The current analysis only uses data from the last two years of the survey due to changes in survey design in 2017 that made the latter two years inconsistent with 2015 and 2016. Respondents from the 2017 survey were not eligible to participate in the 2018 survey. We selected the age groups 19–49, 50– 64, and 65 years to be consistent with those used for the annual national vaccination coverage reports from the Centers for Disease Control and Prevention (CDC) [20].

2.3. Statistical analysis To produce estimates reflective of the adult population in the United States, each sample was balance-weighted using a raking calibration procedure that aligned the responding sample to national benchmarks for respondents’ sex, education level, marital status, presence of chronic medical condition, household income, US census region, internet access at home, and urban/non-urban residence [21]. The raking procedure was used to minimize coverage, selection, and non-response biases; the calibrated weights also adjusted for disproportional distribution of respondents by sociodemographic characteristics. Control totals for the 2017 survey were obtained from the 2015 American Community Survey [22], the 2016 Current Population Survey [23], and the 2015 National Health Interview Survey [24]. Control totals for the 2018 survey were obtained from the 2016 American Community Survey [25], the 2017 Current Population Surveys [18], and the 2016 National Health Interview Survey [26]. All survey estimates were computed using these final weights. We combined data from the two survey years into one dataset for analysis. If a respondent selected ‘‘unsure” for the vaccine’s safety or effectiveness, they were excluded from that analysis, but may have been included in other analyses (i.e., a respondent could have selected an answer for safety but selected unsure for effective, and they would have only been excluded from the effectiveness analysis). We analyzed the data using SAS 9.3 (SAS Institute, Cary, NC) and SAS-callable SUDAAN 11.0 (Research Triangle Institute, Research Triangle Park, NC) to evaluate the proportion of respondents who reported the influenza vaccine was safe and effective. For each age group, we conducted chi-square tests to check for associations between respondents’ sociodemographic, attitude, and knowledge characteristics with reported perception of influenza vaccine safety and effectiveness. For all factors with a p-value  0.05, we conducted pairwise t-tests to determine significant associations between variable levels and a predetermined reference group. Finally, we conducted multivariable logistic regressions to calculate adjusted odds ratios and determine factors independently associated with safety and effectiveness perceptions. All models controlled for respondents’ sex, race/ ethnicity, chronic medical condition(s), education level, household income, insurance status and type (if insured), and the survey year. Statistical significance was defined as p  0.05 for all analyses.

2.2. Study measures

3. Results

The survey included questions that asked respondents to report on their perceptions of safety and effectiveness of the influenza vaccine. We created dichotomous response variables for vaccine safety and effectiveness: belief that the influenza vaccine is safe was defined as a respondent reporting the vaccine is ‘‘somewhat safe” or ‘‘very safe,” compared with ‘‘not too safe” or ‘‘not at all safe”; belief that the influenza vaccine is effective was defined as a respondent reporting the vaccine is ‘‘somewhat effective” or ‘‘very effective,” compared with ‘‘not too effective” or ‘‘not at all effective.” The survey also measured respondents’ knowledge of the influenza vaccine recommendation by providing a list of vaccines and asking respondents to select which, if any, were recommended for at least some adults. We used responses regarding the influenza vaccine to determine any associations between vaccine knowledge and safety or effectiveness perceptions. Respondent data were anonymized and Institutional Review Boards at CDC and Abt Associates determined that this project qualified as research not involving human subjects.

3.1. Respondent characteristics Among panelists invited, 58.2% (n = 2332) and 57.2% (n = 2265) completed the surveys in 2017 and 2018, respectively, for a total of 4597 responses. Over half (54.0%) were aged 19–49 years, 25.9% were aged 50–64 years, and 20.0% were aged  65 years (Table 1). Most respondents were non-Hispanic white (64.3%), reported no underlying chronic medical conditions (70.4%), had private health insurance (68.8%), and lived in an urban area (86.7%). Almost 40% (39.6%) of respondents had a high school education or less and 19.7% of respondents reported an annual household income of less than $25,000 (Table 1). A higher proportion of the 3101 (2017 = 1531; 2018 = 1570) panelists who did not complete the surveys self-reported being non-Hispanic black or Hispanic, female, younger, less educated, and in lower income brackets than the 4597 panelists who completed the surveys. Presence of a chronic medical condition and insurance type/status were unavailable for non-responders.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx Table 1 Sociodemographic characteristics of non-respondents and respondents, Internet panel survey, United States, 2017–2018.

Year 2017 2018 Gender Male Female Age 19–49 years 50–64 years 65 years Race/ethnicitya Non-Hispanic White Non-Hispanic Black Hispanic Non-Hispanic other or multiple race Medical conditionsb No underlying chronic medical Condition Chronic medical condition or weakened immune system Education High school graduate or less Some college College graduate Graduate school Household income Less than $25,000 $25,000 to less than $50,000 $50,000 to less than $75,000 $75,000 or more Health insuranced Private Public None Census region Northeast Midwest South West Area of residencee Metropolitan area Non-metropolitan area

Non-respondents (n = 3101)

Respondents (n = 4597)

N

N

Unweighted %

Unweighted %

Respondents (n = 4597) P-value

N

Weighted %

2332 2265

49.8 50.2

2249 2348

48.3 51.7

2107 1404 1086

54.0 25.9 20.0

1287 1042 1158 1110

64.3 11.9 15.7 8.1

3117 1480

70.4 29.6

1570 920 1398 709

39.6 20.5 27.7 12.2

1067 967 763 1800

19.7 16.7 18.8 44.8

2847 1267 326

68.8 24.2 7.0

759 831 1712 1295

17.9 21.0 37.5 23.6

4134 463

86.7 13.3

0.24 1531 1570

49.4 50.6

2332 2265

50.7 49.3

1359 1742

43.8 56.2

2249 2348

48.9 51.1

2056 746 299

66.3 24.1 9.6

2107 1404 1086

45.8 30.5 23.6

499 910 990 702

16.1 29.3 31.9 22.6

1287 1042 1158 1110

28.0 22.7 25.2 24.1

N/Ac N/A

N/A N/A

3117 1480

67.8 32.2

1374 674 716 337

44.3 21.7 23.1 10.9

1570 920 1398 709

34.2 20.0 30.4 15.4

919 707 524 951

29.6 22.8 16.9 30.7

1067 967 763 1800

23.2 21.0 16.6 39.2

N/A N/A N/A

N/A N/A N/A

2847 1267 326

64.1 28.5 7.3

460 516 1305 820

14.8 16.6 42.1 26.4

759 831 1712 1295

16.5 18.1 37.2 28.2

2814 287

90.7 9.3

4134 463

89.9 10.1

<0.0001

<0.0001

<0.0001

N/A

<0.0001

<0.0001

N/A

0.0003

0.24

Percentages may not add up to 100.0 due to rounding. a Non-Hispanic other or multiple race include at least one of the following: American Indian or Alaskan Native, Asian, Pacific Islander, or Other. b Respondents were considered to have an underlying chronic medical condition if they reported to currently have at least one of the following: lung/breathing problem, liver condition, kidney condition, heart condition, diabetes, pregnant in the last 12 months, or a weakened immune system. c Not available. Presence of an underlying medical condition and insurance status/type were not available for non-respondents. d Private health insurance includes plans paid for by respondent, respondent’s employer, or union and/or military insurance (Tricare, Veteran’s Administration, or CHAMPVA); Public health insurance includes Medicaid, Medicare, Indian Health Service, state sponsored medical plans, and/or other government plans. e Categorization based on Census Current Population Survey Metropolitan Statistical Area (MSA). MSAs have at least one urbanized area with a population of 50,000 or more, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.

3.2. Overall perceptions

3.3. Unadjusted analyses

The majority (86.3%) of respondents reported that influenza vaccine was safe, but adults aged 19–49 years (82.7%) reported significantly lower confidence in its safety compared with those aged 50–64 years (89.5%) or 65 years (91.3%) (Table 2). Likewise, although adults overall still reported believing the influenza vaccine is effective (73.0%), markedly fewer adults aged 19–49 years (68.3%) did so compared with those aged 50–64 years (74.1%) or 65 years (83.4%). Overall, 94.0% of adults reported knowing that the influenza vaccine was recommended for at least some adults. Similarly to safety and effectiveness perceptions, this was reported by fewer adults aged 19–49 years (91.5%) compared with those aged 50–64 years (95.6%) or 65 years (98.1%). Respondents who reported the vaccine as unsafe (n = 482, 10.5%) were asked to identify their main safety concern. ‘‘The vaccine causes bad side effects or adverse reactions” was the most commonly reported concern among respondents (41.6%) (Table 3).

Overall, 12.0% of respondents reported ‘‘unsure” for the safety of influenza vaccine, and 10.2% selected ‘‘unsure” regarding its effectiveness. These respondents were excluded from the analyses below. 3.4. Adults aged 19–49 years Among adults who were aged 19–49 years, those who reported a higher education level, reported an annual household income in the top income bracket, reported that the influenza vaccine was effective, or knew that the vaccine is recommended for at least some adults, were more likely to perceive the influenza vaccine as safe compared with their respective reference groups (Table 4). Fewer adults aged 19–49 years with either public health insurance or no health insurance reported the vaccine was safe. More adults aged 19–49 years who were female, non-Hispanic black, reported

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx

Table 2 Positive safety and effectiveness perceptions* and knowledge of recommendations of respondents for influenza vaccine by age group, Internet Panel Survey, United States, 2017– 2018. Vaccine

Influenza vaccine is safe Influenza vaccine is effective Influenza vaccine is recommended for at least some adults

Overall (Adults  19 years)

Adults 19–49 yearsa

Adults 50–64 years

Adults  65 years

N

Weighted % (95% CI)

Nc

Weighted % (95% CI)

N

Weighted % (95% CI)

N

Weighted % (95% CI)

3965 4000 4281

86.3 (84.4–97.9) 73.0 (70.7–75.1) 94.0 (92.7–95.0)

1729 1768 1887

82.7 (79.6–85.4) 68.3 (64.8–71.7) 91.5 (89.4–93.2)

1245 1237 1332

89.5 (86.9–91.6) 74.1 (70.3–77.6) 95.6 (93.6–97.0)

991 995 1062

91.3 (88.2–93.6) 83.4 (79.5–86.6) 98.1 (96.3–99.0)

P-valueb

<0.0001 <0.0001 <0.0001

Note: Boldface indicates statistical significance (p  0.05 by t-test comparing to the reference group). * Positive safety perceptions refer to a respondent reporting a vaccine is ‘‘somewhat safe” or ‘‘very safe” versus ‘‘not too safe” or ‘‘not at all safe”; positive effectiveness perceptions refer to a respondent reporting a vaccine is ‘‘somewhat effective” or ‘‘very effective” versus ‘‘not too effective” or ‘‘not at all effective.” For knowledge that a vaccine is recommended for at least some adults, respondents were presented with a list of vaccine names and asked to select all that apply (i.e., all that are recommended for at least some adults). a Reference group used for pairwise significance testing. b P-value derived from chi-square to determine subsequent pairwise testing. P-values  0.05 were considered significant and these variables were further tested using pairwise t-tests. c Unweighted frequencies.

Table 3 Main safety concern of respondentsa, Internet Panel Survey, United States, 2017– 2018. Main safety concern

No.b

Weighted % (95% CI)

I believe the vaccine causes the disease I believe that the vaccine causes bad side effects or adverse reactions I believe that the vaccine can interact with antibiotics or other prescription medicine I believe that the ingredients in the vaccine are bad for me Other

117 178

22.6 (16.8–28.5) 41.6 (34.6–48.7)

41

8.6 (4.5–12.7)

141

26.5 (20.6–32.3)

5

0.7 (0.0–1.4)

a

Among respondents reporting a vaccine as ‘‘not too safe” or ‘‘not at all safe.” N = 482. b Unweighted frequencies.

the vaccine as safe, or knew it was recommended for at least some adults reported that the influenza vaccine was effective (Table 5). Those with no health insurance or who lived in a nonmetropolitan area were less likely to report the vaccine was effective. Adults aged 19–49 years were more likely to report the influenza vaccine was effective in 2017 compared with 2018.

3.5. Adults aged 50–64 years The only significant associations for perceived safety of the influenza vaccine among adults aged 50–64 years was reported belief in its effectiveness or knowledge that it is recommended for at least some adults (Table 4). More respondents who identified as non-Hispanic black and non-Hispanic other reported that the influenza vaccine was effective compared with respective reference groups (Table 5). Additionally, more adults who reported the vaccine was safe or knew it was recommended for at least some adults also reported it was effective.

3.6. Adults aged  65 years Respondents 65 years who reported that the vaccine was effective reported that it was safe; however, these results may not be reliable due to relative standard errors (RSE) >0.3 (Table 4). Adults aged  65 years who reported that a vaccine was safe also reported that each vaccine was effective, but the RSE for these results was also >0.3 (Table 5).

3.7. Adjusted analyses After checking for multicollinearity between study variables and finding none, we conducted multiple iterations of multivariable models for each age group to account for potential confounders associated with safety and effectiveness perceptions. Both R-squared values and fitness levels were low (Rsquared < 0.3; p < 0.05), therefore, we do not present these results.

4. Discussion Despite low influenza vaccination rates among adults in the United States, this analysis found perceptions of influenza vaccine safety and effectiveness were relatively high across the three age groups. However, our results suggest that greater efforts may be needed to improve belief in the safety and effectiveness of the vaccine among younger adults. Few studies have examined what sociodemographic factors may influence adults’ beliefs in vaccine safety and effectiveness, and to our knowledge, none have examined these associations by age. Although there were some sociodemographic associations observed, the most important finding from our analysis was that beliefs in influenza vaccine safety and effectiveness had a high positive-association with each other in each age group, which is consistent with previous studies [9,11–15]. Furthermore, as other surveys of adults have found, knowledge of influenza vaccine recommendations was also high among participants [27]. Despite high overall reported knowledge, differences in knowledge between age groups were similar to those seen in reported safety and effectiveness perceptions, and suggest improving awareness of the universal influenza vaccine recommendation may have the greatest impact among younger adults. The majority of adults from all age groups reported that they believed the influenza vaccine was safe. However, among those who perceive the vaccine as not safe, their safety concerns appear to reflect persistent misconceptions regarding the influenza vaccine, and effectively addressing these misconceptions is challenging. A 2015 study found that among persons highly concerned about the safety of influenza vaccine, being told influenza vaccine does not cause the flu paradoxically reduced intent to be vaccinated [28]. A more recent study reflects similar findings, indicating that both benefit- and risk-framed messages resulted in reduced vaccination intentions [29]. These studies, in conjunction with our results, suggest that a better understanding of the nuances involved in patient-perceived vaccine safety is needed, as well as strategic approaches for effectively addressing these concerns.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx Table 4 Respondents’ unadjusted positive perceptions of influenza vaccine safety,* stratified by age group, Internet Panel Survey, United States, 2017–2018. Adults 19–49 years a

Survey year 2017 2018 Gender Malec Female Race/ethnicity Non-Hispanic Whitec Non-Hispanic Black Hispanic Non-Hispanic other or multiple race Medical conditions No underlying chronic medical conditionc Chronic medical condition or weakened immune system Education High school graduate or lessc Some college College graduate Graduate school Household income Less than $25,000c $25,000 to less than $50,000 $50,000 to less than $75,000 $75,000 or more Health insurance Privatec Public None Area of residence Metropolitan areac Non-metropolitan area Believe vaccine is effective Yes Noc Believe vaccine is recommended for adults Yes Noc

N

Weighted % (95% CI)

875 854

85.2 (80.7–88.8) 80.3 (75.8–84.1)

838 891

85.4 (81.2–88.8) 80.1 (75.4–84.0)

316 371 523 519

82.3 82.2 82.1 86.6

1333 396

83.0 (79.6–85.9) 81.3 (73.4–87.3)

533 326 600 270

74.4 82.6 86.5 94.8

(68.4–79.6) (75.5–88.0) (81.0–90.6) (89.4–97.5)

346 336 297 750

71.2 81.4 77.9 88.7

(62.4–78.6) (72.5–87.8) (69.9–84.2) (84.7–91.7)

1144 348 173

87.6 (84.4–90.3) 75.4 (66.6–82.5) 61.6 (49.1–72.7)

1590 139

83.3 (80.1–86.0) 77.8 (65.7–86.5)

1189 457

96.3 (94.0–97.7) 53.8 (46.6–60.8)

1485 131

88.0 (85.0–90.4) 47.1 (34.4–60.3)

Adults  65 years

Adults 50–64 years P-value

b

N

Weighted % (95% CI)

625 620

91.0 (87.0–93.8) 88.0 (84.4–90.8)

624 621

89.6 (85.5–92.6) 89.4 (85.9–92.1)

404 285 269 287

90.0 90.8 85.1 89.1

806 439

88.7 (85.5–91.3) 91.0 (86.5–94.0)

410 272 367 196

87.0 90.5 92.4 88.6

(82.4–90.6) (84.0–94.6) (88.3–95.2) (79.3–94.0)

264 249 178 554

89.4 81.8 90.4 91.4

(83.3–93.4) (73.6–87.8) (83.6–94.6) (87.6–94.1)

882 289 57

90.3 (87.4–92.6) 91.1 (86.4–94.2) 71.3 (50.1–86.1)

1102 143

88.8 (85.9–91.1) 94.0 (86.6–97.4)

928 258

98.2 (96.5–99.1) 64.4 (56.1–71.9)

1162 39

91.7 (89.3–93.6) 46.6 (27.5–66.7)

0.09

N

Weighted % (95% CI)

487 504

92.4 (87.4–95.5) 90.3 (86.1–93.3)

477 514

93.0 (88.0–96.1) 90.0 (85.6–93.1)

441 186 187 177

92.9 83.5 87.4 88.3

502 489

90.5 (85.9–93.7) 92.1 (87.5–95.1)

339 183 278 191

89.2 92.8 93.2 93.7

(83.2–93.2) (86.7–96.3) (87.9–96.3) (86.7–97.1)

262 217 183 329

83.3 93.4 95.5 93.2

(73.5–89.9) (87.8–96.6) (90.3–97.9) (88.7–96.0)

515 468 6

93.4 (90.0–95.8) 88.8 (83.0–92.7) 86.1 (39.8–98.3)d

891 100

92.4 (89.9–94.4) 85.8 (70.4–93.8)

811 144

98.8 (96.6–99.6) 53.5 (41.3–65.3)

960 16

93.4 (90.9–95.2) 51.9 (19.0–83.2)d

0.21

0.07

0.26

0.34 (86.5–92.7) (86.3–93.9) (79.3–89.5) (84.2–92.7)

0.66

0.23 (89.2–95.3) (68.2–92.3) (78.0–93.1) (79.4–93.7)

0.36

<0.0001

0.55

0.24

0.0004

0.55

0.13

0.0001

0.09

0.18

0.33

0.24

0.08

<0.0001

0.27

<0.0001

<0.0001

P-value 0.43

0.95

0.23 (77.2–86.5) (77.3–86.1) (78.0–85.6) (82.9–89.6)

P-value

<0.0001

0.003

0.11

Note: Boldface indicates statistical significance (p < 0.05 by t-test comparing to the reference group). 632 respondents did not answer or were ‘‘unsure” regarding the safety of influenza vaccine. Non-Hispanic other or multiple race include at least one of the following: American Indian or Alaskan Native, Asian, Pacific Islander, or Other. Respondents were considered to have an underlying chronic medical condition if they reported to currently have at least one of the following: lung/breathing problem, liver condition, kidney condition, heart condition, diabetes, pregnant in the last 12 months, or a weakened immune system. Private health insurance includes plans paid for by respondent, respondent’s employer, or union and/or military insurance (Tricare, Veteran’s Administration, or CHAMP-VA). Public health insurance includes Medicaid, Medicare, Indian Health Service, state sponsored medical plans, and/or other government plans. Categorization based on Census Current Population Survey Metropolitan Statistical Area. Metropolitan Statistical Areas (MSAs) have at least one urbanized area with a population of 50,000 or more, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties. * Positive safety perceptions refer to a respondent reporting influenza vaccine is ‘‘somewhat safe” or ‘‘very safe” (as opposed to ‘‘not too safe” or ‘‘not at all safe”). a Unweighted frequencies. b P-value derived from chi-square to determine subsequent pairwise testing. For the purpose of this analysis, p-values  0.05 were considered significant and these variables were further tested using pairwise t-tests. P-values equal to 0.05 in the table that were not subsequently tested using pairwise t-tests were >0.05 after expanding beyond two decimal places and were therefore not considered for further testing. c Reference group used for pairwise significance testing. d Estimate may be unreliable due to small sample size (n < 30) or relative standard error (standard error/estimates) >0.3.

For example, even among persons with safety concerns, a provider recommendation for vaccination is a key predictor of vaccine uptake [12,13,30,31]. That is, ensuring patients receive a strong provider recommendation is key to improving awareness and vaccine utilization. The majority of respondents also reported positive perceptions concerning influenza vaccine effectiveness, yet considerably fewer did so compared with safety or knowledge of recommendations. Addressing negative perceptions concerning influenza vaccine effectiveness may be more challenging than safety perceptions. Suboptimal vaccine matches do occur [32], and respiratory diseases caused by viruses other than influenza often present with similar symptoms, which may minimize the apparent effectiveness of the vaccine in preventing disease. A recent study found that among adults who perceive the influenza vaccine to be effective,

over 76% receive the vaccine every year, and that perception of high vaccine effectiveness was significantly associated with receiving the vaccine every year compared with only some years [16]. The same study also found that the perception of low vaccine effectiveness was associated with adults who had never received the vaccine. In years when there is a good match between vaccine strains and circulating viruses, the influenza vaccine has been shown to reduce risk of illness by 40–60% [33]. Furthermore, it has been shown to reduce the risk of influenza-associated hospitalizations among adults [34,35], and even in cases of vaccine failure (i.e., when a person is vaccinated but still contracts the disease), some studies suggest the vaccine may attenuate symptom severity [36]. Although there is a universal recommendation for the influenza vaccine, far fewer adults aged 19–49 years receive the vaccine

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx

Table 5 Respondents’ unadjusted positive influenza vaccine effectiveness perceptions,* stratified by age group, Internet Panel Survey, United States, 2017–2018. Adults 19–49 years a

Survey year 2017 2018 Gender Malec Female Race/ethnicity Non-Hispanic Whitec Non-Hispanic Black Hispanic Non-Hispanic other or multiple race Medical conditions No underlying chronic Medical conditionc Chronic medical conditions or weakened immune system Education High school graduate or lessc Some college College graduate Graduate school Household income Less than $25,000c $25,000 to less than $50,000 $50,000 to less than $75,000 $75,000 or more Health insurance Privatec Public None Area of residence Metropolitan areac Non-metropolitan area Believe vaccine is safe Yes Noc Believe vaccine is recommended for adults Yes Noc

N

Weighted % (95% CI)

907 861

73.0 (67.8–77.5) 63.7 (58.7–68.5)

854 914

72.2 (67.2–76.6) 64.8 (59.7–69.6)

325 362 553 528

65.7 77.7 70.2 69.8

1361 407

68.0 (64.0–71.7) 69.9 (61.6–77.0)

539 335 622 272

70.4 64.3 65.9 75.8

(64.4–75.7) (55.9–71.9) (59.4–71.9) (66.3–83.2)

339 350 312 767

67.6 63.6 59.4 73.3

(58.7–75.4) (54.1–72.1) (50.9–67.3) (68.3–77.7)

1184 350 173

69.2 (64.9–73.1) 74.0 (65.6–80.9) 53.5 (41.8–64.8)

1626 142

69.9 (66.2–73.3) 56.1 (43.6–67.8)

1400 246

81.0 (77.5–84.0) 16.2 (10.2–24.6)

1514 132

72.6 (68.9–76.0) 40.6 (28.6–53.9)

Adults  65 years

Adults 50–64 years P-value

b

N

Weighted % (95% CI)

614 623

77.1 (70.8–82.3) 71.3 (66.5–75.7)

614 623

74.9 (68.9–80.0) 73.4 (68.3–78.0)

407 282 272 276

71.4 86.3 76.7 79.1

802 435

72.0 (67.2–76.4) 78.3 (71.8–83.6)

415 263 363 196

71.3 77.1 74.7 76.4

(64.2–77.6) (68.1–84.2) (68.3–80.2) (67.3–83.5)

261 244 179 553

80.5 73.8 76.5 71.2

(73.3–86.0) (64.6–81.2) (66.3–84.3) (65.2–76.5)

886 282 53

71.2 (66.6–75.4) 86.0 (79.6–90.6) 78.6 (60.4–89.9)

1087 150

75.9 (72.0–79.4) 63.3 (50.7–74.3)

1062 124

82.8 (79.0–86.0) 13.6 (7.1–24.6)d

1162 38

75.8 (71.9–79.4) 43.8 (24.0–65.7)

0.01

N

Weighted % (95% CI)

490 505

85.0 (78.7–89.7) 81.7 (76.7–85.9)

484 511

85.4 (79.0–90.0) 81.7 (76.6–85.9)

446 190 183 176

84.0 79.0 84.7 78.6

511 484

80.6 (75.0–85.2) 86.0 (80.3–90.2)

334 185 283 193

79.9 85.5 85.9 88.0

(72.6–85.6) (77.7–90.9) (79.9–90.3) (80.1–93.0)

269 214 183 329

79.3 81.1 91.3 83.4

(70.2–86.2) (71.7–87.9) (84.1–95.3) (76.8–88.4)

516 468 8

87.1 (82.2–90.8) 79.6 (73.2–84.8) 44.1 (11.4–83.0)d

894 101

84.3 (80.6–87.4) 78.5 (62.9–88.7)

878 77

91.2 (88.0–93.6) 12.8 (4.7–30.5)d

961 20

84.6 (80.8–87.7) 69.8 (39.9–88.9)d

0.13

0.04

0.32

0.001 (66.2–76.1) (81.1–90.1) (70.5–81.9) (73.3–83.9)

0.66

0.59 (79.3–87.8) (65.0–88.4) (75.5–90.9) (69.0–85.8)

0.11

0.19

0.14

0.69

0.02

0.34

0.20

0.03

0.07

0.004

0.04

0.06

0.07

<0.0001

0.40

<0.0001

<0.0001

P-value 0.37

0.69

0.01 (60.0–71.0) (72.6–82.0) (65.7–74.3) (65.2–74.0)

P-value

<0.0001

0.01

0.23

Note: Boldface indicates statistical significance (p < 0.05 by t-test comparing to the reference group). 597 respondents did not answer or were ‘‘unsure” regarding the effectiveness of influenza vaccine. Non-Hispanic other or multiple race include at least one of the following: American Indian or Alaskan Native, Asian, Pacific Islander, or Other. Respondents were considered to have an underlying chronic medical condition if they reported to currently have at least one of the following: lung/breathing problem, liver condition, kidney condition, heart condition, diabetes, pregnant in the last 12 months, or a weakened immune system. Private health insurance includes plans paid for by respondent, respondent’s employer, or union and/or military insurance (Tricare, Veteran’s Administration, or CHAMP-VA). Public health insurance includes Medicaid, Medicare, Indian Health Service, state sponsored medical plans, and/or other government plans. Categorization based on Census Current Population Survey Metropolitan Statistical Area (MSA). MSAs have at least one urbanized area with a population of 50,000 or more, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties. * Positive efficacy perceptions refer to a respondent reporting influenza vaccine is ‘‘somewhat effective or ‘‘very effective.” a Unweighted frequencies. b P-value derived from chi-square to determine subsequent pairwise testing. For the purpose of this analysis, p-values  0.05 were considered significant and these variables were further tested using pairwise t-tests. P-values equal to 0.05 in the table that were not subsequently tested using pairwise t-tests were >0.05 after expanding beyond two decimal places and were therefore not considered for further testing. c Reference group used for pairwise significance testing. d Estimate may be unreliable due to small sample size (n < 30) or relative standard error (standard error/estimates) >0.3

annually compared with older adults [6,37]. Perceptions regarding the influenza vaccine among this younger age group are underrepresented in the literature and studies overwhelmingly focus on specific populations (e.g., pregnant women or healthcare workers), rather than the general population. Although knowledge of the vaccine recommendation was positively associated with safety and effectiveness perceptions among most adults in our analysis, other factors, such as education and income levels, were observed exclusively among younger adults. Similarly, higher census-tract level poverty has been shown to be associated with higher influenza-related hospitalizations compared with low census tract-level poverty [38]. Therefore, it is important to consider targeted messaging appropriate for education and income levels to improve influenza immunization perceptions and vaccine uptake. Efforts to foster positive immunization practices, beliefs, and atti-

tudes could be especially impactful among the youngest adults in this age group, whose lifelong health seeking behaviors may still be forming [39]. There were few sociodemographic factors significantly associated with vaccine perceptions among adults aged 50–64 years. One notable observation, however, was that respondents who identified as non-Hispanic black or non-Hispanic ‘‘other” race were more likely to report that they believed the influenza vaccine was effective than non-Hispanic white respondents. Similarly, nonHispanic black respondents aged 19–49 were more likely to report they believed the vaccine is effective (Table 5). These findings directly contrast results from earlier studies suggesting that nonHispanic white adults tend to have more positive attitudes towards the vaccine than racial/ethnic minorities [9,30,40,41]. However, one recent study suggests such findings may be an oversimplifica-

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

C.S. Lutz et al. / Vaccine xxx (xxxx) xxx

tion of racial disparities often seen in adult vaccination; there are significant differences in vaccination perceptions and behavior within African American groups, and this nuanced information is often overlooked or missing in published comparative studies that simply look at black versus white respondents [42]. For example, Quinn et al. reported significant differences between education and income levels among an all-back sample regarding respondents’ self-reported knowledge of, actual knowledge of, trust in, hesitancy towards, confidence in, and uptake of the influenza vaccine [42]. Similarly, respondents to our survey had significantly higher education and income levels overall compared with nonrespondents, which may explain the association between race and perceived influenza effectiveness opposite of those typically observed in studies that consider black respondents as one homogenous group. Adults aged  65 years and older are at greater risk of serious complications from influenza disease compared with younger adults, and tend to bear the greatest burden of severe disease during a typical influenza season [43]. For example, it has been estimated that between 70% and 90% of seasonal influenza-related deaths and between 50% and 70% of seasonal influenza-related hospitalizations occur among persons in this age group [2,3]. Due to the greater risk of severe illness and death among adults in this age group, recommendations for the influenza vaccine have existed much longer than for other groups [44,45], which is consistent with older adults’ higher vaccination coverage rates compared with younger adults [7,8]. In addition, this also likely explains the lack of differences in safety and effectiveness perceptions of the vaccine between sociodemographic groups among adults aged  65 years. The multivariable logistic regression models failed to generate statistically meaningful results, and few sociodemographic characteristics were associated even at the bivariate level. In addition, some significant associations, such as higher perceived effectiveness among racial/ethnic minorities, directly contrasts with data on adult vaccination coverage [10,20]. This suggests factors beyond the patient characteristics considered in this report may contribute to safety and effectiveness perceptions among adults, and that other factors beyond safety and effectiveness perceptions may contribute to adult vaccination coverage. A strong recommendation from a healthcare provider is regularly cited as a motivating factor in adult patients’ decisions to receive vaccination, and several studies have demonstrated that receiving a recommendation from a trusted provider may alleviate vaccine safety concerns [12,13,30,31,46]. However, perceived safety barriers may persist despite effective patient-provider communication. There is limited information regarding the conversations providers have with their patients in the literature. In the absence of prospective observations of these interactions, intervention efforts must rely on retrospective patient and provider reports, which may be subject to memory error and social desirability bias. Understanding how healthcare providers make vaccine recommendations during these critical encounters may better explain discrepancies in patient perceptions of vaccine safety and effectiveness than sociodemographic characteristics, such as those considered here. Furthermore, researchers should consider other factors that may be better correlated with actual vaccine behavior than safety and effectiveness perceptions, and may in turn be better explained by sociodemographic characteristics, such as vaccination habit and social influence [47]. 4.1. Limitations Our analysis is subject to limitations. The surveys were not developed using a specific theoretical model, completion rates were moderate, and there were significant sociodemographic dif-

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ferences between respondents versus non-respondents. Nonresponse bias can result if respondents and non-respondents differ in key elements of the analysis, and can remain despite poststratification weighting. Nonetheless, probability-based panel survey findings have been found to have results similar to administrative data and high-quality government surveys [48]. Over 10% of respondents were excluded from our analyses due to being unsure about the safety and effectiveness of the vaccine. While this is an important finding regarding the education needs for both influenza vaccination and adult vaccines overall, differences among those who reported definitively regarding the vaccine’s safety and effectiveness versus those who were unsure were not assessed and may have influenced results. Respondents reported any vaccines received within the last 12 months, but the survey did not ask respondents to identify during which influenza season they received an influenza vaccine. Therefore, although the correlation between perceived safety, effectiveness, and vaccine acceptance has been established in other studies [11–13], we were unable to measure vaccine coverage in this analysis. Results may have been affected if adults in our sample were disproportionately vaccinated or unvaccinated. Finally, R-squared values were low and goodness of fit statistics were inconsistent between the multivariable models, which suggests factors beyond those considered in this report may contribute to safety and effectiveness perceptions among adults. 5. Public health implications Overall, adults from all age groups believe the influenza vaccine is safe, effective, and recommended for at least some adults. However, perceptions of its effectiveness are more limited, and these beliefs were lowest among younger adults. Our results suggest that efforts may be most needed for younger adults overall to improve awareness of the recommendations, safety, and effectiveness of influenza vaccination. Increasing awareness and providing clear recommendations may lead to improved perceptions of vaccines and greater uptake among adults. However, considering the already overwhelmingly positive perceptions among adults, any improvements would be minor and likely have a limited effect on coverage. Efforts to understand why, despite positive perceptions, adults are still choosing to forego the vaccine may be more informative. Future studies investigating vaccination habits, attitudes, and social influence may provide such insights. The influenza vaccine provides cost-effective preventive care for reducing illness, hospitalization, disability, and death from a vaccinepreventable disease [33–36,49]. Addressing suboptimal influenza vaccination coverage among adults in the United States would make a substantial contribution to public health. Financial disclosure The authors report no financial disclosures. Funding support This work was funded by the U.S. Centers for Disease Control and Prevention. This project was also supported in part by an appointment to the Research Participation Program for the Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Immunization Services Division, administered by the Oak Ridge Institute of Science and Education, US Department of Energy, United States through an agreement between the CDC. The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

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C.S. Lutz et al. / Vaccine xxx (xxxx) xxx

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.

References [1] Molinari NA, Ortega-Sanchez IR, Messonnier ML, Thompson WW, Wortley PM, Weintraub E, et al. The annual impact of seasonal influenza in the US: measuring disease burden and costs. Vaccine 2007;25(27):5086–96. https:// doi.org/10.1016/j.vaccine.2007.03.046. [2] Reed C, Chaves SS, Daily Kirley P, Emerson R, Aragon D, Hancock EB, et al. Estimating influenza disease burden from population-based surveillance data in the United States. PLoS ONE 2015;10(3):. https://doi.org/10.1371/journal. pone.0118369e0118369. [3] Kostova D, Reed C, Finelli L, Cheng PY, Gargiullo PM, Shay DK, et al. Influenza illness and hospitalizations averted by influenza vaccination in the United States, 2005–2011. PLoS ONE 2013;8(6):. https://doi.org/10.1371/journal. pone.0066312e66312. [4] Uyeki TM. Influenza ITC33-ITC48. Ann Intern Med 2017;167(5). https://doi. org/10.7326/AITC201709050. [5] Fiore AE, Uyeki TM, Broder K, Finelli L, Euler GL, Singleton JA, et al. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR Recomm Rep 2010; 59(RR-8):1–62. [6] Centers for Disease Control and Prevention. Flu Vax View Prior Flu Seasons. https://www.cdc.gov/flu/fluvaxview/earlier-seasons.htm. Accessed March 9, 2018. . [7] Centers for Disease Control and Prevention. Flu Vaccination Coverage, United States, 2016-17 Influenza Season. https://www.cdc.gov/flu/ fluvaxview/coverage-1617estimates.htm. Accessed December 14, 2018. [8] Centers for Disease Control and Prevention. Estimates of Influenza Coverage among Adults - United States, 2017-18 Flu Season. https://www.cdc.gov/flu/ fluvaxview/coverage-1718estimates.htm. Accessed December 14, 2018. [9] Crouse Quinn S, Jamison AM, Freimuth VS, An J, Hancock GR. Determinants of influenza vaccination among high-risk Black and White adults. Vaccine 2017;35(51):7154–9. https://doi.org/10.1016/j.vaccine.2017.10.083. [10] Lu PJ, O’Halloran A, Williams WW, Lindley MC, Farrall S, Bridges CB. Racial and ethnic disparities in vaccination coverage among adult populations in the U.S. Am J Prev Med 2015;49(6 Suppl 4):S412–25. https://doi.org/10.1016/j. amepre.2015.03.005. [11] Santibanez TA, Mootrey GT, Euler GL, Janssen AP. Behavior and beliefs about influenza vaccine among adults aged 50–64 years. Am J Health Behav 2010;34 (1):77–89. https://doi.org/10.5993/AJHB.34.1.10. [12] Wray RJ, Jupka K, Ross W, Dotson D, Whitworth AR, Jacobsen H. How can you improve vaccination rates among older African Americans?. J Family Practice 2007;56(11):925–9. [13] Ding H, Black CL, Ball S, Fink RV, Williams WW, Fiebelkorn AP, et al. Influenza vaccination coverage among pregnant women – United States, 2016–17 influenza season. MMWR - Morb Mortal Wkly Rep 2017;66(38):1016–22. https://doi.org/10.15585/mmwr.mm6638a2. [14] Wheelock A, Thomson A, Sevdalis N. Social and psychological factors underlying adult vaccination behavior: lessons from seasonal influenza vaccination in the US and the UK. Expert Rev Vaccines 2013;12(8):893–901. https://doi.org/10.1586/14760584.2013.814841. [15] Padilla ME, Frietze G, Shenberger-Trujillo JM, Carrillo M, Loya AM. Influenza and intentions to vaccinate in an underserved hispanic population: the role of theoretically derived constructs. J Pharm Pract 2018. https://doi.org/10.1177/ 0897190018810595. 897190018810595. [16] Abbas KM, Kang GJ, Chen D, Werre SR, Marathe A. Demographics, perceptions, and socioeconomic factors affecting influenza vaccination among adults in the United States. PeerJ 2018;6:. https://doi.org/10.7717/peerj.5171e5171. [17] Chi RC, Neuzil KM. The association of sociodemographic factors and patient attitudes on influenza vaccination rates in older persons. Am J Med Sci 2004;327(3):113–7. https://doi.org/10.1097/00000441. [18] United States Census Bureau. Current Population Survey: March 2017 Annual Social and Economic (ASEC) Supplement. http://thedataweb.rm.census.gov/ ftp/cps_ftp.html#cpsmarch. [19] GfK. KnowledgePanelÒ Design Summary. http://www.knowledgenetworks. com/knpanel/docs/knowledgepanel(R)-design-summary-description.pdf. Accessed February 20, 2018. [20] Williams WW, Lu PJ, O’Halloran A, Kim DK, Grohskopf LA, Pilishvili T, et al. Surveillance of Vaccination Coverage among Adult Populations - United States, 2015. MMWR Surveill Summ 2017;66(11):1–28. https://doi.org/10.15585/ mmwr.ss6611a1. [21] Battaglia MPHD, Frankel MR. Practical considerations in raking survey data. Survey Practice 2009;2(5).. https://doi.org/10.29115/SP-2009-0019. [22] United States Census Bureau. American Community Survey (ACS): 2015 ACS 1year PUMS. http://www.census.gov/programs-surveys/acs/data/pums.html.

[23] United States Census Bureau. Current Population Survey: March 2016 Annual Social and Economic (ASEC) Supplement. http://thedataweb.rm.census.gov/ ftp/cps_ftp.html#cpsmarch. [24] Centers for Disease Control and Prevention. National Health Interview Survey: 2015 Data Release. http://www.cdc.gov/nchs/nhis/nhis_2015_data_release. htm. [25] United States Census Bureau. American Community Survey (ACS): 2016 ACS 1-year PUMS. http://www.census.gov/programs-surveys/acs/data/pums. html. [26] Centers for Disease Control and Prevention. National Health Interview Survey: 2016 Data Release. http://www.cdc.gov/nchs/nhis/nhis_2016_data_release. htm. [27] Lu PJ, O’Halloran A, Kennedy ED, Williams WW, Kim D, Fiebelkorn AP, et al. Awareness among adults of vaccine-preventable diseases and recommended vaccinations, United States, 2015. Vaccine 2017;35(23):3104–15. https://doi. org/10.1016/j.vaccine.2017.04.028. [28] Nyhan B, Reifler J. Does correcting myths about the flu vaccine work? An experimental evaluation of the effects of corrective information. Vaccine 2015;33(3):459–64. https://doi.org/10.1016/j.vaccine.2014.11.017. [29] Kim S, Pjesivac I, Jin Y. Effects of message framing on influenza vaccination: understanding the role of risk disclosure, perceived vaccine efficacy, and felt ambivalence. Health Commun 2017:1–10. https://doi.org/10.1080/ 10410236.2017.1384353. [30] Lindley MC, Wortley PM, Winston CA, Bardenheier BH. The role of attitudes in understanding disparities in adult influenza vaccination. Am J Prev Med 2006;31(4):281–5. https://doi.org/10.1016/j.amepre.2006.06.025. [31] Fuchs J. The provision of pharmaceutical advice improves patient vaccination status. Pharm Pract (Granada) 2006;4(4):163–7. [32] Xie H, Wan XF, Ye Z, Plant EP, Zhao Y, Xu Y, et al. H3N2 mismatch of 2014–15 northern hemisphere influenza vaccines and head-to-head comparison between human and ferret antisera derived antigenic maps. Sci Rep 2015;5:15279. https://doi.org/10.1038/srep15279. [33] Centers for Disease Control and Prevention. Seasonal influenza vaccine effectiveness, 2004-2018. https://www.cdc.gov/flu/ professionals/vaccination/effectiveness-studies.htm. Accessed April 16, 2019. [34] Rondy M, El Omeiri N, Thompson MG, Leveque A, Moren A, Sullivan SG. Effectiveness of influenza vaccines in preventing severe influenza illness among adults: a systematic review and meta-analysis of test-negative design case-control studies. J Infect 2017;75(5):381–94. https://doi.org/10.1016/j. jinf.2017.09.010. [35] Talbot HK, Griffin MR, Chen Q, Zhu Y, Williams JV, Edwards KM. Effectiveness of seasonal vaccine in preventing confirmed influenza-associated hospitalizations in community dwelling older adults. J Infect Dis 2011;203 (4):500–8. https://doi.org/10.1093/infdis/jiq076. [36] Deiss RG, Arnold JC, Chen WJ, Echols S, Fairchok MP, Schofield C, et al. Vaccineassociated reduction in symptom severity among patients with influenza A/ H3N2 disease. Vaccine 2015;33(51):7160–7. https://doi.org/10.1016/ j.vaccine.2015.11.004. [37] Centers for Disease Control and Prevention. AdultVaxView: Vaccination Coverage Among Adults in the United States, National Health Interview Survey, 2016. https://www.cdc.gov/vaccines/imz-managers/coverage/ adultvaxview/pubs-resources/NHIS-2016.html. Accessed July 17, 2018. [38] Hadler JL, Yousey-Hindes K, Perez A, Anderson EJ, Bargsten M, Bohm SR, et al. Influenza-related hospitalizations and poverty levels – United States, 2010– 2012. MMWR Morb Mortal Wkly Rep 2016;65(5):101–5. https://doi.org/ 10.15585/mmwr.mm6505a1. [39] Sawyer SM, Afifi RA, Bearinger LH, Blakemore SJ, Dick B, Ezeh AC, et al. Adolescence: a foundation for future health. Lancet 2012;379(9826):1630–40. https://doi.org/10.1016/S0140-6736(12)60072-5. [40] Wooten KG, Wortley PM, Singleton JA, Euler GL. Perceptions matter: beliefs about influenza vaccine and vaccination behavior among elderly white, black and Hispanic Americans. Vaccine 2012;30(48):6927–34. https://doi.org/ 10.1016/j.vaccine.2012.08.036. [41] Quinn SC, Jamison A, Freimuth VS, An J, Hancock GR, Musa D. Exploring racial influences on flu vaccine attitudes and behavior: results of a national survey of White and African American adults. Vaccine 2017;35(8):1167–74. https://doi. org/10.1016/j.vaccine.2016.12.046. [42] Quinn SC, Jamison A, An J, Freimuth VS, Hancock GR, Musa D. Breaking down the monolith: understanding flu vaccine uptake among African Americans. SSM Popul Health 2018;4:25–36. https://doi.org/10.1016/j. ssmph.2017.11.003. [43] Centers for Disease Control and Prevention. People 65 years and older & influenza. https://www.cdc.gov/flu/about/disease/65over.htm. Accessed January 7, 2019. [44] Eickhoff TC. Immunization against influenza: rationale and recommendations. J Infect Dis 1971;123(4):446–54. [45] Francis Jr T. Immunization of selected population groups against influenza. The rationale of current recommendations. Arch Environ Health 1967;14 (5):747–8. [46] Malosh R, Ohmit SE, Petrie JG, Thompson MG, Aiello AE, Monto AS. Factors associated with influenza vaccine receipt in community dwelling adults and their children. Vaccine 2014;32(16):1841–7. https://doi.org/10.1016/ j.vaccine.2014.01.075.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004

C.S. Lutz et al. / Vaccine xxx (xxxx) xxx [47] Lin CJ, Nowalk MP, Toback SL, Rousculp MD, Raymund M, Ambrose CS, et al. Importance of vaccination habit and vaccine choice on influenza vaccination among healthy working adults. Vaccine 2010;28(48):7706–12. https://doi.org/ 10.1016/j.vaccine.2010.07.009. [48] Yeager DSKJ, Chang L, Javitz HS, Levendusky MS, Simpser A, Wang R. Comparing the accuracy of RDD telephone surveys and internet surveys

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conducted with probability and non-probability samples. Public Opinion Quarterly 2011;75(4):709–47. https://doi.org/10.1093/poq/nfr020. [49] Belongia EA, Simpson MD, King JP, Sundaram ME, Kelley NS, Osterholm MT, et al. Variable influenza vaccine effectiveness by subtype: a systematic review and meta-analysis of test-negative design studies. Lancet Infect Dis 2016;16 (8):942–51. https://doi.org/10.1016/S1473-3099(16)00129-8.

Please cite this article as: C. S. Lutz, R. V. Fink, A. J. Cloud et al., Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017–2018, Vaccine, https://doi.org/10.1016/j.vaccine.2019.12.004