Key Takeaways

• A systematic review and meta-analysis found that the four-component meningococcal serogroup B (4CMenB) vaccine was associated with approximately 80% effectiveness against serogroup B invasive meningococcal disease (IMD) in fully vaccinated infants and children.
• Across five countries included in the primary meta-analysis, pooled vaccine effectiveness was 79.7%, with consistent findings across multiple sensitivity analyses.
• Vaccine effectiveness was substantially lower among partially vaccinated infants and children than among those who completed the recommended vaccination schedule.
• Multiple national immunization programs also reported marked reductions in serogroup B IMD incidence following implementation of routine 4CMenB vaccination.

Although invasive meningococcal disease is uncommon, it can progress rapidly and is associated with substantial morbidity and mortality, particularly in infants and young children. Since the introduction of the four-component meningococcal serogroup B (4CMenB) vaccine into national immunization programs, observational studies have evaluated its effectiveness in routine clinical practice. Synthesizing these data may help inform vaccination policy and guide implementation strategies across diverse healthcare settings.

A systematic review and meta-analysis published in Clinical Infectious Diseases evaluated the real-world effectiveness and population impact of 4CMenB vaccination against serogroup B invasive meningococcal disease. Investigators searched PubMed, Embase, Web of Science, and Cochrane databases for observational studies published through November 2024. Seventeen studies reported in 20 publications met inclusion criteria. Five studies from Australia, England, Italy, Spain, and Portugal contributed to the primary meta-analysis evaluating vaccine effectiveness in fully vaccinated infants and children. Random-effects models were used to calculate pooled vaccine effectiveness estimates, and additional sensitivity and subgroup analyses were performed.

The pooled vaccine effectiveness among fully vaccinated infants and children was 79.7% (95% CI, 70.4%-86.1%). Individual study estimates ranged from 71% to 95.6%, with low between-study heterogeneity. Sensitivity analyses produced similar estimates after excluding individual studies, restricting analyses to countries with similar vaccination schedules, and evaluating alternative study populations. Among partially vaccinated infants and children, pooled vaccine effectiveness was 41.1% (95% CI, 16.1%-58.7%), suggesting lower protection without completion of the recommended vaccination series.

Several included studies also evaluated vaccine impact at the population level following implementation of routine immunization programs. Reported reductions in serogroup B IMD incidence included approximately 63% among infants and 79% among adolescents in South Australia, approximately 70% to 75% among vaccine-eligible children in England, regional reductions of 84% to 100% in Italy, and reductions ranging from 53% to 92% in Canadian vaccination programs. Because all included studies were observational, the findings are subject to potential confounding and bias. Most studies were conducted in high-income countries with established surveillance systems, and available data were insufficient to perform pooled analyses in adolescents or evaluate vaccine effectiveness according to time since vaccination. Differences in vaccination schedules and study methodology may also limit direct comparisons across countries.

The authors conclude that real-world evidence supports high effectiveness of 4CMenB vaccination against serogroup B invasive meningococcal disease in fully vaccinated infants and children. These findings provide quantitative evidence supporting the continued use of routine 4CMenB immunization programs and may help inform future vaccination policy.

Clinician Questions

What was the pooled effectiveness of 4CMenB vaccination against serogroup B invasive meningococcal disease?

Across five observational studies included in the primary meta-analysis, pooled vaccine effectiveness among fully vaccinated infants and children was 79.7% (95% CI, 70.4%-86.1%), with consistently high estimates across sensitivity analyses.

How did vaccine effectiveness differ between fully and partially vaccinated children?

Fully vaccinated infants and children experienced substantially greater protection than partially vaccinated children. Pooled vaccine effectiveness was 79.7% after completion of the recommended vaccination schedule compared with 41.1% among partially vaccinated individuals.

What did studies report about the population-level impact of 4CMenB vaccination?

Several national immunization programs reported substantial declines in serogroup B invasive meningococcal disease following implementation of routine 4CMenB vaccination, with reductions observed in Australia, England, Italy, and Canada.