FROM THE JOURNAL OF PEDIATRICS
During a 2012 pertussis outbreak in Oregon, unvaccinated or poorly vaccinated children were affected significantly earlier than fully vaccinated children were, according to Steve G. Robison, MPH, and Juventila Liko, MD, MPH, from the Immunization Program, Oregon Health Authority, Portland.
A total of 351 pertussis cases in children aged 2 months to 10 years were reported in Portland and the upper Willamette Valley from Jan. 1 to Nov. 1, 2012. Children who were unvaccinated accounted for 76 (22%) of the reported cases, and children who were poorly vaccinated accounted for 50 of the 275 (18%) cases in vaccinated children.
The median date of onset for unvaccinated and poorly vaccinated children was 117 days after Jan. 1, and the median date of onset for fully vaccinated children was 158 days after Jan. 1. Mean date of onset was 133 days and 159 days after Jan. 1, respectively. In zip codes with both unvaccinated and vaccinated cases, children who were unvaccinated were 3.2 times more likely to have an earlier onset date.
“Children who are not immunized represent a dynamic risk of spreading disease in an outbreak and have an impact that is greater than simply lessening overall community immunity levels. Diseases such as pertussis may spread across areas through the choice of parents to not immunize or to limit immunizations. Once locally present, pertussis will spread to the unimmunized and vulnerable, who in turn through the weight of exposure, may then ignite a wider outbreak in vaccinated populations,” the investigators noted.
Find the full study in the Journal of Pediatrics ( doi: 10.1016/j.jpeds.2016.12.047 ).
