Tdap booster in teens less effective after initial acellular vaccine series

July 1, 2016

An analysis of data on the incidence of pertussis shows that although acellular pertussis (Tdap) vaccine had a positive impact among adolescents in the 4 years after it was introduced in 2005, in 2010 pertussis incidence in this age group began to increase more rapidly than it did in all other age groups.

An analysis of data on the incidence of pertussis shows that although acellular pertussis (Tdap) vaccine had a positive impact among adolescents in the 4 years after it was introduced in 2005, in 2010 pertussis incidence in this age group began to increase more rapidly than it did in all other age groups. This abrupt shift in incidence occurred in the same year that 11-year-olds represented the first group of children to have received acellular vaccines for all doses of the childhood series, following the 1997 transition from whole pertussis to acellular vaccines. These findings indicate that a Tdap booster vaccine in adolescence has a diminished effect among those who were primed with acellular pertussis vaccine in early childhood.

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The extended analysis of reported pertussis cases between 1990 and 2014 shows that pertussis incidence was highest among infants aged younger than 1 year throughout the period. Pertussis rates were comparable among all other age groups until the late 2000s when the pertussis burden increased among children aged 1 to 10 years; between 2007 and 2011, the incidence of pertussis in children in this age group was 1 to 2 times higher than in adolescents aged 11 to 18 years. However, when trends reversed in 2010, rates of pertussis among 11- to 18-year-olds increased at a faster rate than it did in all other age groups combined, and by 2014 adolescents had overtaken all but young infants in pertussis incidence (Skoff TH, et al. JAMA Pediatr. 2016;170[5]:453-458).

Commentary: This means that pertussis is not going away and, despite Tdap boosters, incidence will continue to rise as more children initially vaccinated with acellular pertussis vaccine move through adolescence. In the words of the researchers, “[S]usceptible individuals will continue to accumulate in the population.” Until a new solution is devised, it is up to us to continue to think about pertussis, recognize it early, and initiate treatment to decrease spread. -Michael G Burke, MD

Ms Freedman is a freelance medical editor and writer in New Jersey. Dr Burke, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. The editors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.