A new British mathematical modelling study published in The Lancet HIV has found that adding pre-exposure prophylaxis for gay men at high risk of HIV to relatively modest increases in HIV testing, and immediate treatment for those diagnosed, could substantially cut the number of gay men infected by 2020. The researchers conclude that without these interventions, the number of gay men acquiring HIV is unlikely to decrease by 2020, even if the UK achieves the ‘90-90-90’ target of 73% of all people with HIV virally suppressed by this time.

The study, which was funded by the UK Health Protection Agency (now Public Health England) also finds that behavioural changes such as reducing the number of regular sexual partners could also make substantial inroads into HIV incidence but are less powerful as individual interventions.

It finds that increases in sexual partner numbers or condomless sex would substantially reduce the effectiveness of PrEP, testing and treatment, but even a complete cessation of condom use would not totally negate the effect of other interventions: only this, combined with a decrease in HIV testing, would do so.