- Email: [email protected]
Underimmunization drives community outbreaks of pertussis
THE EDITORS’ PERSPECTIVES muscle tone and cry pattern on a 0- to 3-point rating scale. In 220 near-term and full-term infants admitted to their hospital with severe hyperbilirubinemia, El Houchi et al noted that regardless of the total serum bilirubin, infants with BIND scores of 3-4 or more were at increased risk for persistent neurologic abnormalities at 3-5 months of age. The etiology of jaundice for the infants in this study was not described, and the gestational age of the infants was not precisely known. These two factors suggest that further replication of these findings is needed to understand the usefulness of the BIND score across a variety of at-risk populations. However, in this study, El Houchi et al have shown that serial neurologic examinations are an important and cost-effective adjunct to the total serum bilirubin in the evaluation and management of jaundice that should be useful to pediatricians worldwide. Article page 51 ▶
Underimmunization drives community outbreaks of pertussis — Sarah S. Long, MD
O
bservational studies have suggested that underimmunized individuals can be the starting point of an outbreak of vaccine preventable infections, such as measles and pertussis. Clusters of underimmunized individuals also can be the weak link in herd (community) protection against transmission following introduction of an infectious agent. Robison and Liko, at the Oregon Health Authority, further hypothesized that during a widespread pertussis outbreak in Oregon in 2012, spread of infection between communities was driven by social networks of people less likely to immunize their children. They further posited that if this hypothesis was correct, cases of pertussis among the underimmunized would be expected to cluster in the early stages of an outbreak. Starting at the beginning of 2012, pertussis cases in the 2-month to 10-year cohort in the Oregon Sentinel Surveillance region were stratified by immunization status, zip code, and date of disease onset. Results showed that unimmunized and underimmunized cases had calendar onset of disease 41 days earlier than fully or mostly immunized cases. This and other analyses of their data support the hypothesis that social networks of parents who choose deliberately not to immunize their children can represent a dynamic risk for driving community-wide outbreaks of pertussis – a risk more consequential than individuals merely playing a role in local failure to achieve herd/community protection. The authors make another interesting point, which is that economic disadvantage was primarily responsible for social networks of underimmunized children prior to the Vaccines for Children Program. Currently, it is parental choice not to vaccinate that threatens their own and the community’s children. Article page 159 ▶
Cumulative Percentage of Pertussis Cases
100%
90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
Non-Immunized
April 2017
Week of Onset
Poorly Immunized
Fully or Mostly Immunized
3
Underimmunization drives community outbreaks of pertussis — Sarah S. Long, MD
O
bservational studies have suggested that underimmunized individuals can be the starting point of an outbreak of vaccine preventable infections, such as measles and pertussis. Clusters of underimmunized individuals also can be the weak link in herd (community) protection against transmission following introduction of an infectious agent. Robison and Liko, at the Oregon Health Authority, further hypothesized that during a widespread pertussis outbreak in Oregon in 2012, spread of infection between communities was driven by social networks of people less likely to immunize their children. They further posited that if this hypothesis was correct, cases of pertussis among the underimmunized would be expected to cluster in the early stages of an outbreak. Starting at the beginning of 2012, pertussis cases in the 2-month to 10-year cohort in the Oregon Sentinel Surveillance region were stratified by immunization status, zip code, and date of disease onset. Results showed that unimmunized and underimmunized cases had calendar onset of disease 41 days earlier than fully or mostly immunized cases. This and other analyses of their data support the hypothesis that social networks of parents who choose deliberately not to immunize their children can represent a dynamic risk for driving community-wide outbreaks of pertussis – a risk more consequential than individuals merely playing a role in local failure to achieve herd/community protection. The authors make another interesting point, which is that economic disadvantage was primarily responsible for social networks of underimmunized children prior to the Vaccines for Children Program. Currently, it is parental choice not to vaccinate that threatens their own and the community’s children. Article page 159 ▶
Cumulative Percentage of Pertussis Cases
100%
90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
Non-Immunized
April 2017
Week of Onset
Poorly Immunized
Fully or Mostly Immunized
3