Gonorrhoea remains a significant global health concern, with men who have sex with
men (MSM) being disproportionately affected. Recent evidence suggests that outer membrane
vesicle (OMV) meningococcal vaccines, such as the most widely used 4CMenB vaccine,
may provide cross-protection against gonorrhoea.We aimed to evaluate the effectiveness
of OMV vaccines against gonorrhoea through a systematic review and meta-analysis.PubMed,
Embase, and CENTRAL were searched from inception to 10 July 2024. Original articles
were included if they investigated gonorrhoea incidence among recipients of OMV vaccines.
Our primary endpoint was the incidence of gonorrhoea among vaccinated and unvaccinated
individuals. The risk of bias was assessed using ROBINS-I, and the RoB-2 tools. A
random-effects model with a 95 % confidence interval (CI) was applied to estimate
pooled effect sizes. The study was registered on PROSPERO, CRD42024530848.We identified
12 eligible studies for qualitative analysis. Six retrospective studies and one prospective
study were included in the quantitative analysis, of which six investigated the 4CMenB
OMV vaccine. The pooled analysis yielded a vaccine effectiveness (VE) of 38 % [95
% CI:22 %-50 %; I2 = 55 %]. Including only the 4CMenB vaccine, VE was 41 % (OR = 0.59;
95 % CI:0.46-0.76; I2 = 44 %). Complete vaccination might offer 24 % greater protection
compared to partial vaccination (OR = 0.76; 95 % CI:0.31-1.85; I2 = 86 %). VE declined
in 2-3 years post-vaccination. Four studies were rated as low risk, four as moderate
risk, and four as having serious risk of bias. The certainty of the evidence was graded
as moderate. The main limitations include the retrospective nature and the high heterogeneity
of the included studies.OMV vaccines offer moderate protection against gonorrhoea.
4CMenB OMV vaccine should be prioritised for sexually active individuals over non-OMV
alternatives, with emphasis on completing the full vaccination series. Consideration
should be given to administering 4CMenB to high-risk MSM groups specifically for gonorrhoea
prevention.
