British researchers have shown that pre-exposure prophylaxis (PrEP) is highly protective against HIV for gay and other men who have sex with men (MSM).

While ARVs are traditionally used to treat people who are HIV positive, certain ARVs can also be used to prevent HIV negative men from becoming infected, a method referred to as pre-exposure prophylaxis (PrEP).

The PROUD study looked at whether offering daily PrEP to MSM was in fact a reliable way to prevent them from becoming infected if exposed to the virus.

The results released at the Conference on Retroviruses and Opportunistic Infections (CROI) in Seattle, Washington last week indicate that PrEP is highly protective for this group, reducing the risk of infection by 86%.

The researchers highlighted that MSM who took part in the trial were at very high risk of HIV and that PrEP is highly effective in a real world setting.

The sexual health research clinics that took part in the PROUD study were able to integrate PrEP into their routine HIV risk reduction package with ease. Participants incorporated PrEP into existing risk reduction strategies, which included condom use.

The researchers concluded that PrEP offers a major new opportunity to curb newly acquired HIV infections among MSM.

The study was launched in 2012, enrolling 545 participants at 13 sexual health clinics in England. The 86% protection from daily (Truvada) PrEP reported by the study, is the highest reported from a randomised controlled trial of PrEP to date.

“These results are extremely exciting and show PrEP is highly effective at preventing HIV infection in the real world. Concerns that PrEP would not work so well in the real world were unfounded," commented Sheena McCormack, Professor of Clinical Epidemiology at the MRC Clinical Trials Unit at UCL, and Chief Investigator of the PROUD study.

"These results show there is a need for PrEP, and offer hope of reversing the epidemic among men who have sex with men in this country. The findings we’ve presented today are going to be invaluable in informing discussions about making PrEP available through the NHS (National Health Service)," she said.

Dr Richard Gilson, principal investigator for the PROUD study at the Mortimer Market Centre, a sexual health service run by Central and North West London NHS Foundation Trust, added: “Working at a central London sexual health clinic, it is clear to me that there are gay men attending sexual health clinics in the UK who are at high risk of catching HIV infection but who are willing and able to take tablets regularly, which can dramatically reduce their risk of becoming HIV positive.

"This will not suit everyone, and may not be needed indefinitely, but for at least some individuals for some of the time it should be considered as an important additional measure, that will help to reduce the persistently high rate of new infections that we are still seeing," he said.

PrEP use by gay, bisexual and other men who have sex with men has already been endorsed by America’s Centres for Disease Control and Prevention (CDC) and the World Health Organisation (WHO).

PrEP is not currently offered in public hospitals and clinics in South Africa, although those who can afford to pay for it may request a prescription from a private doctor or a gay-friendly clinic, such as OUT in Pretoria or Health4Men in Johannesburg and Cape Town. The use of PrEP will require regular HIV tests and monitoring.