A study in which gay men at risk of HIV are given medication to protect them from contracting the disease is being fast-tracked, following initial successes.

The Proud study involved giving antiretroviral drugs to HIV-negative people to reduce their risk of becoming infected if they are at high risk of exposure to the virus. This is known as PrEP, or pre-exposure prophylaxis: it protects the person before they have been exposed to the virus.

The trial was being run in two stages: one group started taking Truvada immediately, while a second group would be given the drug after the study had been running for 12 months. However, initial analysis showed better than expected results, and the group of doctors running the trial have decided that the people in the second group would be able to start on Truvada immediately.

Placebo controlled trials have already shown that PrEP works to protect against acquiring HIV and that protection is best when the daily tablet is taken consistently. All participants are offered regular testing for HIV and sexually transmitted infections, condoms and safer sex support.

The exact number of HIV infections that PrEP prevented is not yet known, but clinics that are involved are aiming to have follow-up visits (including HIV tests) with all trial participants by the end of the year, which means results will be available in early 2015.

The Independent Data Monitoring Committee, who reviewed the interim data from the trial, is confident this follow-up will not change the overall conclusion of the trial, but will provide greater accuracy in the results. Continued follow-up of participants will also allow the Proud study to answer questions about longer-term adherence, changes to risk behaviour, and drug resistance.

Dr Rosemary Gillespie, Chief Executive at Terrence Higgins Trust, said: ‘This is potentially the most exciting development in HIV prevention in some years. For a trial to be fast-tracked in this way is rare, and shows just how much confidence researchers have in PrEP as a tool to reduce the spread of HIV. A number of questions remain unanswered, including how PrEP will be made available and who will be able to access it. The Proud study has accelerated their part of the process. We will now be looking to the NHS to match that pace, and act swiftly to ensure those most at risk of HIV in the UK can access PrEP.’