A daily pill can effectively protect gay men against infection with HIV, a UK trial has shown, which experts say now offers hope of reversing the virus’s spread.

Taking the drug, called Truvada, could become a daily routine for men who have sex with men in the same way that the contraceptive pill is for women, some believe. NHS England will now study the results to determine whether it is cost effective to provide it for men at risk of infection.

Truvada is already widely used in the US after it was approved by the US Food and Drug Administration in 2012 as the first daily pill to help prevent HIV in some high-risk groups. It is available through most private health insurance plans in the US and the state Medicaid system.

The study, carried out in 12 NHS trusts, showed that Truvada, which is already used to treat people with HIV, cut infections among men who have sex with men by 86%. Experts are delighted by the success rate because the study was carried out in “real world” situations, with participants free to use the pills or not as they chose. Fears that men would not take the pills regularly proved to be unfounded.

The study, Proud (Pre-exposure Option for reducing HIV in the UK: immediate or Deferred), follows a number of trials in other countries and has achieved a success rate higher than all of them. Launched in 2012, it recruited 545 men who have sex with men who were considered to be at high risk of HIV infection through sexual health clinics. Those who were recruited had a median of 10 partners in the previous 90 days.

Half the group were randomly allocated to get Truvada immediately, while the other half were given it after a year. Among the men who started the drug straight away, there were three HIV infections, but among the other group who did not have the drug, there were 19. The results were presented at the Conference on Retroviruses and Opportunistic Infections in Seattle, US, and will be published later.

“These results are extremely exciting and show PrEP [pre-exposure prophylaxis] is highly effective at preventing HIV infection in the real world,” said Sheena McCormack, professor of clinical epidemiology at the MRC Clinical Trials Unit at University College London, and chief investigator of the study.

“Concerns that PrEP would not work so well in the real world were unfounded. 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.”

Richard Gilson, from the Mortimer Market Centre, a sexual health service run by Central and North West London NHS Foundation Trust, and principal investigator for the Proud study, said the drug “appeared to be an important and practical solution” for high risk men who were happy to take it regularly.

Prevention efforts at the moment are falling short, he said, because HIV rates among men who have sex with men are still high.

“I think the NHS should certainly consider this,” he said. The next bit of evidence would be a cost-benefit analysis from the trial, but he added, “I shall be surprised if it is not cost-effective at the usual threshold they apply, at least for individuals with this high-risk profile.”

The cost of Truvada, made by Gilead, is around £360 a person a month and there are thought to be around 10,000 to 15,000 people in the high-risk category, those who have multiple partners and sometimes do not use condoms. Public Health England estimates there are around 2,500 new infections among gay men every year.

The National Aids Trust called for the pills to be made available on the NHS. Deborah Gold, its chief executive, said it had to be good value compared to the cost of treating even those men in the trial who were in the group who had deferred access to the drug and became infected.

“Over the course of their lifetime the treatment of those 19 men will cost the NHS nearly £7m,” she said. “So the financial argument is clear, as is the ethical one. PrEP needs to be available on the NHS as soon as possible for all those who need it.”

Dr Michael Brady, medical director at Terrence Higgins Trust, said: “PrEP is, quite simply, a game-changer. We know that most gay men use condoms most of the time, and that this has prevented tens of thousands of HIV infections since the epidemic began in the UK. However, we also know that condomless sex vastly increases the risk of HIV being transmitted.”

PrEP offered another line of defence alongside condoms and regular testing. “It is not a vaccine and it won’t be for everyone, but once approved, we expect it to significantly increase the momentum in our fight against the virus,” he said.

