Associate Professor University of British Columbia Faculty of Medicine Vancouver, British Columbia, Canada
Background: Neisseria meningitidis causes invasive meningococcal disease (IMD) in children and adolescents, including bacteremia and meningitis. Bacteria are categorized into different groups based on the polysaccharide capsule, and group B (NmB) organisms are a leading cause of endemic disease globally. Protein vaccines to target NmB (MenB vaccines) have been developed to reduce NmB disease, and have been implemented in routine childhood immunization programs in some countries. Objective: To evaluate the overall vaccine effectiveness (VE) and impact of MenB vaccines in public health programs globally against NmB IMD. Design/Methods: We conducted a systematic review and meta-analysis to evaluate MenB VE and impact in children and adolescents. We searched the literature via MEDLINE, EMBASE, CINAHL, CENTRAL, and grey literature from inception to August 2023. Post-implementation observational studies of any licensed MenB vaccine and any schedule were included. Control groups included unvaccinated or historical pre-vaccine cohorts. Meta-analysis for VE and incident rate ratios (IRR) were performed using random effects by inverse variance weighting, based on the outcome of NmB IMD. Results: Of 7,785 studies that were identified, 12 studies include VE and/or impact analysis (7 studies from Europe, 3 from Australia and 2 from Canada), of which 8 were included in the meta-analysis; others were excluded from meta-analysis due to high heterogeneity. All the eight studies evaluated the 4CMenB vaccine. The overall pooled VE was 91% (95% CI 87% to 96%) in all children aged < 6 years, with a pooled VE of 84% (95% CI 73% to 97%) in infants aged < 12 months and 57% (95% CI 41% to 79%) in children aged 12-23 months. The pooled IRR was 0.50 (95% CI 0.37-0.69) in children aged < 6 years, with a pooled IRR of 0.40 (95% CI 0.31-0.51) in infants aged < 12 months, 0.53 (95% CI 0.20-1.40) in children aged 12-23 months, and 0.25 (95% CI 0.13-0.51) in adolescents aged 15-19 years.
Conclusion(s): The 4CMenB vaccine has been effective against NmB in countries where it has been introduced and evaluated, suggesting this could be a promising component of the World Health Organization Global Road Map to ‘Defeat Meningitis by 2030’. To provide context, in these countries published analyses have predicted that vaccination with 4CMenB could reduce the risk of IMD caused by 66% to 100% of NmB isolates. More data are required on population-wide effectiveness of other MenB vaccines, as well as effectiveness data on long-term protection after vaccination to inform future vaccination strategies.
