The Tdap booster vaccine provided moderate protection against whooping cough during the first year post-vaccination but its efficacy decreased to <9% just 4 years post-vaccination among teenagers who received the newer form of the acellular pertussis vaccine as infants and children, according to a new study published in Pediatrics.  

Babies and infants receive the vaccine to protect against diphtheria, tetanus, and pertussis. In the 1990s, the U.S. switched from offering the whole cell pertussis (DTwP) to acellular pertussis (DTaP) vaccines. Now all five childhood doses (ages 2, 4, 6, 12-18 months, 4-6 years) use the DTaP vaccine. The U.S. and other countries have observed a rise in whooping cough cases after the switch to the new vaccine despite high levels of coverage. The Advisory Committee on Immunization Practices (ACIP) recommended a booster acellular pertussis (Tdap) vaccine for all adolescents aged 11–12 years.

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For the study, researchers assessed Tdap efficacy among adolescents within Kaiser Permanente Northern California during pertussis outbreaks in 2010 and 2014. Tdap coverage was seen in over 90% of adolescents but they exhibited the highest incidence of pertussis of any age group in 2014. Study authors noted that routine vaccination at ages 11–12  did not prevent the epidemic. Moreover, an increasing number of adolescents who have received only the newer acellular pertussis vaccines remain at higher risk of contracting whooping cough.  

Nicola Klein, MD,PhD, co-director of the Kaiser Permanente Vaccine Study Center, stated that Tdap may contain whooping cough “more effectively if it is administered to adolescents in anticipation of a local outbreak rather than on a routine basis at age 11 or 12.” 

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