The booster shot that is supposed to protect adolescents from whooping cough isn’t working as well as public health officials would hope, according to a study published Friday in the journal Pediatrics.
The study concludes that for every year that passes after a child receives the tetanus, diphtheria and pertussis vaccine, known as Tdap, their protection against the respiratory disease wanes by about 35 percent. While some other vaccines are known to wear off over time, that’s unusually fast. And it’s distressing because whooping cough, or pertussis, spreads easily and can be deadly in infants, researchers said.
After a 2010 outbreak in California that sickened about 9,000 people and resulted in the
deaths of 10 infants, the state mandated the Tdap booster for all kids entering
7th grade.
Despite that effort, another outbreak erupted in 2014,
affecting even more people and causing another three infant deaths. Researchers with Kaiser Permanente in Northern California
looked back through medical records to see if and when vaccinated kids came
down with whooping cough during the two outbreaks.
The researchers had previously used the same data to analyze
the effectiveness of the initial round of childhood shots against whooping
cough, known as the DTaP series. They concluded that after the last DTaP shot
is administered — usually around age 5 — immunity wears off at a rate of 42
percent a year. Their new study is a follow-up that reports on the
effectiveness of the booster shot, which is given to kids at age 11 or 12. “We’re all trying to figure out what’s special about
pertussis and how we can induce more durable immunity,” Dr. Kathryn Edwards, a
pediatrician and researcher who was not involved in the study, told Healthline.
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