Waning Immunity Seen Post-Tdap Booster in Preteens
(HealthDay News) — The tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine given to preteens loses a large measure of effectiveness within a few years, new research reveals. The study findings are published online May 4 in Pediatrics.
The study team zeroed in on a pertussis epidemic in the state of Washington in 2012. Five thousand people became ill with pertussis, many of them in their early teens, despite the state's 86% Tdap coverage rate. Focus was placed on about 1,700 teens born between 1993–2000 – children who would have received the newer vaccine. This group experienced 450 cases of pertussis.
Overall, Tdap effectiveness for this group was pegged at about 64%, but that plummeted to 34% 2–4 years post-inoculation, the investigators found. Similar findings emerged from a Wisconsin study, leading the U.S. Centers for Disease Control and Prevention to attribute the recent spike in pertussis to a waning of Tdap effectiveness.
Going forward, CDC investigators said two things are needed: a better understanding of how exactly the pertussis bacteria works and an improved vaccine. But for the time being they don't recommend any shift in vaccine protocols.