A 6-year Prospective, Observational, Multi-Center Post-Marketing Surveillance of the Safety of Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis (Tdap) Vaccine in Korea

BACKGROUND: Incidence of whooping cough is increasing in Korea. Since 2011, occurrence among adolescents and adults has risen putting vulnerable neonates at risk. National immunization guidelines now include Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) vaccination during pregnancy and as a cocooning strategy (i.e., vaccinating adults and adolescents in contact with neonates). This study assessed post-marketing Tdap (Boostrix®, GSK, Belgium) vaccine safety in subjects ≥ 10 years. METHODS: This open, non-comparative multi-center study was conducted over six years at 10 hospitals in Korea. Subjects received Tdap in normal clinical practice according to local prescribing information. All adverse events (AEs) were recorded, classified as expected or unexpected, and severity and relationship to Tdap were assessed. RESULTS: The analysis included 672 Korean subjects (mean age, 44 years; range, 11–81), 451 were women and 211 were pregnant. Ninety subjects experienced 124 AEs (incidence 13.39%) of which six were serious AEs (SAEs) assessed as not related to vaccination, and 51 were non-SAEs related to vaccination (mostly administration site reactions). Overall 65/124 AEs were unexpected; the most common were 14 constipation, 5 dyspepsia, 4 common cold and 4 premature labor cases. One case of common cold was assessed as possibly related to vaccination. Pregnancy outcome was ‘live infant, no apparent congenital anomaly’ in 195 subjects (92.42%) or ‘lost to follow-up’ in 16 subjects. CONCLUSION: Tdap administration to Korean subjects ≥ 10 years, including pregnant women, for the prevention of diphtheria, tetanus and pertussis was shown to have a well-tolerated safety profile. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01929291