Long-Term Protection Against Invasive Meningococcal B Disease and Gonococcal Infection 5 Years After Implementation of Funded Childhood and Adolescent 4CMenB Vaccination Program in South Australia: An Observational Cohort and Case-Control Study

Abstract

BACKGROUND: A publicly funded 4CMenB program has been implemented in South Australia since 2018. We aimed to evaluate vaccine effectiveness (VE) and vaccine impact on invasive meningococcal B (MenB) disease and gonococcal infections 5 years after the program introduction. METHODS: Vaccine impact was assessed using a Poisson or negative binomial regression model, and VE was estimated using both cohort screening and case-control methods. VE against the subsequent gonococcal infection was measured using a Cox regression model. RESULTS: Relative reductions of 72.7% (95% confidence interval [CI], 38.0%-88.0%) and 76.2% (41.6%-90.3%) in the incidence of MenB disease were observed in infants aged <1 year and adolescents aged 15-18 years, respectively. VE against MenB disease for the 3-dose schedule was 98.5% (95% CI, 81.9%-99.9%) in children and 92.3% (34.3%-99.1%) for the 2-dose vaccination in adolescents. VE for 2-dose vaccination against gonococcal infections in adolescents was 39.1% (95% CI, 31.3%-46.0%). Lower VE estimates were demonstrated in those >5 years compared to within 5 years since vaccination (-6.3% (95% CI, -44.5% to 21.8%) vs 41.8% (34.0%-48.7%). The VE against the subsequent gonococcal infection was 27.0% (adjusted hazard ratio, 0.730 [95% CI, .540-.988]), comparing fully vaccinated with unvaccinated case patients. CONCLUSIONS: 4CMenB demonstrates high protection against MenB disease in children and adolescents at 5 years. Moderate protection against the first and subsequent gonococcal infections in adolescents was observed up to 5 years after vaccination, with waning evident after 5 years.

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