The impact of vaccination on Neisseria gonorrhoeae antimicrobial resistance and prevalence in men who have sex with men: a mathematical modelling study

Background. Neisseria gonorrhoeae (gonorrhoea) and antimicrobial-resistant (AMR) gonorrhoea infections disproportionately affect men who have sex with men (MSM). Vaccine development is challenging, but a N. meningitidis (group B) vaccine given to children and young adults was associated with a ca. 30% reduction in gonorrhoea diagnoses. We investigated the impact of vaccination on N. gonorrhoeae AMR development and transmission in MSM. Methods. We developed a compartmental model of N. gonorrhoeae transmission among MSM. AMR to ceftriaxone was incorporated as a stepwise increases in minimum inhibitory concentrations and eventual resistance (MIC drift). We estimated the impact of a partially protective vaccine (reducing susceptibility; 2-years protection) targeting high sexual activity MSM on AMR and prevalence until 2050. We performed sensitivity analyses assuming different levels of vaccine effectiveness (VE) and other modes of vaccine action. Findings. Gonorrhoea model prevalence was 3.4% (95% credible interval 3.2% - 3.8%) in all MSM, 12.5% (95% credible interval 12.1% - 12.7%) in high sexual activity MSM. A vaccine with 30% VE cannot prevent AMR, even with high uptake or durable protection. However, it increases time to AMR development by several years. For a fixed uptake of 40% a vaccine needs a minimum VE of 90% to prevent AMR development completely. A vaccine providing complete protection to infection for those vaccinated was most effective in reducing population prevalence and preventing AMR. Interpretation. A vaccine that has limited efficacy for the prevention of gonorrhoea could delay AMR development in MSM, providing time for developing new antimicrobials and more efficacious vaccines.