Evaluating the potential impact of a vaccine on gonorrhoea prevalence in a remote Australian Indigenous setting: a mathematical modelling study

Background Neisseria gonorrhoeae has a significant impact on global sexual and reproductive health. Its notification rates are substantially higher among Aboriginal and Torres Straight Islander peoples compared with non-Indigenous people (1651 vs 79 per 100,000 population). The emergence of multidrug-resistant N. gonorrhoeae strains highlights the need for a gonococcal vaccine. Methods We developed an individual based mathematical model of N. gonorrhoeae transmission among 16–36-year-old Indigenous people living in remote communities in Australia to assess potential vaccine impact on gonorrhoea prevalence. We considered various vaccine characteristics (i.e. efficacy and duration of protection of a hypothetical vaccine) and levels of annual vaccination uptake, and different vaccination implementation strategies targeting specific age groups to assess the impact on N. gonorrhoeae prevalence in this population that could be achieved once a vaccine becomes available. Results Vaccination could be effective in reducing N. gonorrhoeae prevalence under all scenarios investigated. For conservative vaccine scenarios, at 5 years post-vaccine implementation, the relative reduction observed ranged from 15 to 28% if there was 40% annual vaccine uptake by the 16–19-year-old age group of a vaccine with 25–50% protective efficacy and 5 years duration of protection. A reduction of 95 or 98% was possible at 5 or 10 years, respectively, if there was 80% uptake by the 16–36-year-old age group of a vaccine with 75% protective efficacy and 10 years duration of protection. Conclusion Vaccination could lead to substantial reductions in N. gonorrhoeae prevalence among remote Indigenous communities, even with a vaccine that offers only partial efficacy, if vaccination is provided annually to a moderately large proportion (≥40%) of unvaccinated individuals.