Pre-exposure prophylaxis prevents HIV infection in gay men

An H9 T cell, coloured in blue, infected with the human immunodeficiency virus (HIV), yellow. Photo: AP

An H9 T cell, coloured in blue, infected with the human immunodeficiency virus (HIV), yellow. Photo: AP

Daily HIV medication (tenofovir-emtricitabine) to HIV negative gay men who run a high risk of getting infected is highly effective in preventing new infections, a clinical trial found. There was no evidence of increase in other sexually transmitted infections, as well. The daily medication did not cause any serious adverse drug reactions.

These were some of the important outcomes of a study by a team led by Sheena McCormack of the Medical Research Council (MRC) Clinical Trials Unit at University College London, UK. The results were published recently in The Lancet. “Our findings strongly support the addition of pre-exposure prophylaxis (PrEP) to the standard of prevention for men who have sex with men at risk of HIV infection,” they write.

The randomised, placebo-controlled trial was carried out between November 29, 2012 and April 30, 2014 on 544 HIV negative gay men who had a high risk of contracting HIV. While three infections occurred in the group that got the HIV medication daily, 20 were reported in the placebo arm. Thus people in the group that got the pre-exposure prophylaxis had an 86 per cent relative reduction in risk of acquiring HIV compared with the other arm.

Based on early evidence of effectiveness, the steering committee of the trial recommended in October, 2014, that all participants in the placebo arm be given the pre-exposure prophylaxis medication to prevent HIV infection.

The efficacy of tenofovir-based drugs to prevent HIV infections when given as a pre-exposure prophylaxis is well known; seven trials have confirmed its effectiveness. But the current trial, by using a placebo arm, avoided any bias due to risk compensation. Participants are likely to engage in riskier sexual practices such as avoiding condom use when they perceive to be protected by the medication.

“Our results refute concerns that the effectiveness of PrEP would be compromised when used in clinical practice, and the reduction in HIV incidence exceeded that reported from any placebo-controlled trial. The incidence of HIV infection among men not on PrEP was high (nine cases per 100 person-years), implying that the offer of PrEP is likely to attract individuals who are most likely to benefit from it,” they write. The important implications of the study are that PrEP when part of a public health programme can have a “major role in preventing” new HIV infections and “curtailing the HIV epidemic.”

“The results from PROUD suggest that pragmatic deployment of PrEP must be part of any relevant primary HIV prevention strategy,” Kenneth H. Mayer from Harvard Medical School and Chris Beyrer from Johns Hopkins University, Baltimore, write in an accompanying Comment piece. Since a large number of people with HIV are unaware of their infection and about 20 million HIV infected people are not on treatment, the best way to win the war against HIV is to prevent infection.

It is, however, essential that other preventive measures be used along with the pre-exposure prophylaxis (PrEP) for best results.

“The time for cautionary speculation is over: HIV prevention services should be expanded worldwide by offering PrEP routinely to those who could benefit,” the Comment piece notes.

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Printable version | Oct 7, 2022 5:23:47 pm |