Background: Although decennial adult boosters of tetanus and diphtheria toxoids are recommended in Canada and the United States, a second dose of pertussis vaccine is not currently recommended for adults.
Methods: This open-label, postmarketing, multicenter study evaluated the tolerability and immunogenicity of a second dose of an adult formulation of tetanus, diphtheria, and pertussis vaccine (Tdap) in adolescents and adults 5 years after a first dose.
Results: A total of 545 participants from previous Tdap vaccine studies, ranging in age from 15 to 69 years, participated in this study. Of these participants, 94.2% had at least one solicited adverse event after the booster dose such as injection-site erythema (28.6%), swelling (25.6%), or pain (87.6%) or a systemic adverse event such as myalgia (61.0%), headache (53.2%), malaise (38.2%), or fever (6.5%). These adverse events were slightly more frequent than after the initial dose. Postvaccination, 100% of participants had a tetanus antibody level ≥0.10IU/mL and 95% had a diphtheria antibody level ≥0.10IU/mL. For pertussis, 82.1% (pertussis toxoid), 96.7% (filamentous hemagglutinin), 95.6% (pertactin), and 99.8% (fimbriae) had a postvaccination antibody threshold of ≥50EU/mL.
Conclusion: A second dose of Tdap vaccine 5 years after the initial dose was well tolerated and immunogenic in adolescents and adults.
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