Giving healthy gay men in the UK HIV drugs before they are exposed to the virus could prevent “a large number” of cases and thus significantly reduce incidence of the disease, claims new research funded by Public Health England and published in The Lancet. 

Transmission of HIV between men who have sex with men (MSM) has stayed level over the last decade, highlighting the need for new preventative strategies and prompting research into estimating the effect of various potential interventions.

Using a mathematical model, the researchers calculated that offering pre-exposure prophylaxis alongside regular HIV testing and early treatment to just a quarter of MSM at high risk of contracting HIV could prevent around 7,400 new infections (44% of total incidence) by 2020.

A key concern is that PrEP may increase sexual risk-taking in men, as they know they are protected from contracting the disease, by increasing their levels of unprotected sex or the number of partners. However, analysis carried out as part of the study indicate that even a substantial increase in such activity is unlikely to completely counteract the strong preventative benefit.

All-in-all, the findings indicate that alongside other key strategies pre-exposure prophylaxis could have a significant impact on the number of HIV cases, and the researchers warn that, without it, “HIV incidence in MSM in the UK is unlikely to decrease substantially by the end of this decade”.

"Current prevention efforts in the UK that focus on correct and consistent condom use and regular HIV testing have been falling short. HIV rates among men who have sex with men remain high with around 2800 men who have sex with men becoming infected with HIV in 2014, and the trend shows no sign of abating," noted lead author Narat Punyacharoensin who conducted the research while at the London School of Hygiene & Tropical Medicine, London, UK. 

"Our results show that pre-exposure prophylaxis offers a major opportunity to curb new infections and could help reverse the HIV epidemic among men who have sex with men in the UK”.