BACKGROUND: Increases in sexually transmitted infections (STIs) among gay and bisexual men (GBM) over the past decade have coincided with declines in condom use and rapid uptake of HIV pre-exposure prophylaxis (PrEP). We explored the impact of an antimicrobial gel-based point-of-sex intervention (gel-PSI) with a lower efficacy for reducing gonorrhoea transmission risk than condoms on population-level gonorrhoea incidence among GBM in Victoria, Australia. METHODS: A deterministic compartmental model of HIV and gonorrhoea transmission was used to project annual gonorrhoea incidence from 2020 to 2025. Individuals were classified as HIV-negative (PrEP or non-PrEP-users) or HIV-positive, and further stratified gonorrhoea risk (high/low). All possible scenarios where between 0-100% of GBM using condoms transitioned to gel-PSI (considered a downgrade in protection) and 0-100% of GBM not using condoms transitioned to gel-PSI (considered an upgrade in protection), with gel-PSI efficacy ranging from 20-50% were run. RESULTS: The baseline scenario of no gel-PSI uptake (status quo) projected 94,367 gonorrhoea infections between 2020-2025, with an exponentially increasing trend in annual infections. For a gel-PSI efficacy of 30%, a net reduction in cumulative gonorrhoea incidence was projected, relative to the status quo, for any ratio of proportion of condom-users ‘downgrading’ to proportion of non-condom-users ‘upgrading’ to gel-PSI use of less than 2.6. Under the supposition of equal proportions of condom-users and non-condom-users switching to gel-PSI, a relative reduction was projected for any gel-PSI efficacy greater than 16%. CONCLUSIONS: Our model suggests that the introduction of a gel-PSI could have benefits for controlling gonorrhoea transmission among GBM, even in scenarios where the gel-PSI is considerably less efficacious than condoms and when gel-PSI uptake leads to consequent reductions in consistent condom use.
Link to publisher’s web site