Background Gonorrhoea infection is increasing and becoming harder to treat. In England, incidence among men who have sex with men (MSM) has increased eight-fold since 2008, reaching ≥21,000 cases in 2017. This epidemic, coupled with the growing threat of potentially untreatable antibiotic-resistant infection, has renewed interest in a gonococcal vaccine. Previous vaccine development attempts have failed; however, observational evidence suggesting the MeNZB meningococcal B vaccine is partially protective against gonorrhoea, with 31% effectiveness but uncertain duration, indicates it may be possible to develop a suitable vaccine.

Methods We fitted a stochastic transmission-dynamic model, incorporating asymptomatic and symptomatic infection and heterogeneous sexual behaviour, to gonorrhoea incidence in MSM in England over 2008–17 using particle Markov Chain Monte Carlo methods. Bayesian forecasting, considering realistic vaccination strategies under different scenarios of antibiotic resistance, determined how vaccine effectiveness and duration of protection affect population-level impact, and examined feasibility of achieving WHO’s target of reducing gonorrhoea incidence by 90% between 2016 and 2030.

Results Even a partially-effective vaccine could have a substantial impact if protection lasts long enough. In a worst-case scenario of untreatable gonorrhoea, vaccinating all MSM attending sexual health clinics with a 58% effective vaccine protecting for ≥12 years (with boosters if required), or a 66% effective vaccine lasting ≥6 years, reduces expected incidence below the WHO target. A vaccine conferring 30% protection for 2–4 years reduces expected incidence in 2030 by 34% if gonorrhoea becomes untreatable, but if ≥80% of gonorrhoea cases are treatable then incidence is reduced by 95%.

Conclusion Our statistically rigorous assessment shows that even a partially-effective vaccine, delivered through a practical targeting strategy, could have a substantial benefit in reducing gonorrhoea incidence in the context of an epidemic with rising antibiotic resistance. Our model can help design trials to measure vaccine effectiveness and duration of protection and assess cost-effectiveness of vaccination strategies.

Disclosure No significant relationships.