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Rapidly waning Tdap offers little long-term protection against pertussis
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Tdap vaccine waned rapidly and provided only limited, short-term protection against pertussis when administered to adolescents as a booster for DTaP, according to recent research in Pediatrics.
“This study investigated the effectiveness of Tdap against pertussis in a highly vaccinated population during two successive epidemics,” Nicola P. Klein, MD, PhD, of the Northern California Kaiser Permanente Vaccine Study Center, and colleagues wrote. “We demonstrate that among a cohort of teenagers who have exclusively received acellular pertussis vaccines, Tdap provides moderate protection 1 year after vaccination and then protection wanes rapidly.”
Nicola P. Klein
The researchers followed 279,493 children who received DTaP in infancy, from a single medical research center, from age 10 years until either a pertussis diagnosis, administration of a second Tdap vaccine, disenrollment in the program or end of the study period. Children who were vaccinated with Tdap were compared with unvaccinated participants to model pertussis risk in relation to vaccination status.
Study results showed that among all study participants, there were 1,207 pertussis cases recorded. Vaccine effectiveness was calculated at 68.8% (95% CI, 59.7%-75.9%) during the first year of Tdap vaccination, which decreased to 56.9% (95% CI, 41.3%-68.4%) after 2 years, 25.2% (95% CI, –4.3% to 46.4%) after 3 years and 8.9% (95% CI, –30.6% to 36.4%) after 4 years. Further, children not recently vaccinated with Tdap were significantly more likely to test positive for pertussis, when compared with those recently vaccinated (HR per year = 1.35; 95% CI, 1.22-1.5).
“Because Tdap provides reasonable short-term protection against pertussis, Tdap may more effectively contain pertussis if it is administered to adolescents in anticipation of a local pertussis outbreak rather than on a routine basis,” Klein and colleagues wrote. “While awaiting development of new vaccines that will provide long-lasting protection against pertussis, we should consider alternate Tdap immunization strategies for adolescents.” – by David Costill
Disclosure: The researchers report no relevant financial disclosures.
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