'Game changer' HIV drug cuts infection risk by 86%

Behind the Headlines

Wednesday February 25 2015

Condoms remains the most effective way to prevent getting HIV

The drug stops HIV from replicating

"Scientists hail discovery of 'game-changer' that cuts the risk of infection among gay men by 86%," The Independent reports. The drug, Truvada, has proved very successful in a "real-world" trial involving 545 participants.

Truvada is currently used as part of a treatment plan for people with HIV. It stops the virus from replicating, which helps protect the immune system.

Researchers wanted to see if it could also prevent the infection taking hold in the first place and have now presented initial results at a conference.

They recruited gay men, other men who have sex with men (MSM) and transgender women who were HIV negative and at high risk of HIV infection from 13 sexual health clinics in England. They randomly assigned them to either immediately start taking Truvada each day, or to wait and start taking it 12 months later.

The researchers also wanted to see if taking the medication made people more likely to increase their sexual risk-taking behaviour because they thought they were protected.

It is reported that both groups had the same rate of other sexually transmitted infections (STIs), an indication that sexual risk-taking did not change. The incidence of HIV infection in their first year of the study was much smaller in the Truvada group, at three people compared to 19 in the group who had to wait for a year before starting taking Truvada.

The researchers plan to submit the study to a peer-reviewed journal in April and are working with a range of stakeholders to determine whether a Truvada service could be commissioned across the NHS for high-risk individuals.


HIV – reducing your risk

The two most effective methods of preventing catching HIV are:

  • using a condom during penetrative sex, including anal sex
  • never share needles if you are an injecting drug user

Read more about preventing HIV

Where did the story come from?

The study was carried out by researchers from the Medical Research Council Clinical Trials Unit at University College London, Public Health England and 12 NHS trusts across England. It was co-funded by the Medical Research Council and Public Health England.

The results of the study were presented at the Conference on Retroviruses and Opportunistic Infections in Seattle, Washington. The study has not yet been published, so has not gone through external peer review to ensure the methodology and findings are reliable. The Medical Research Council reports that the study will be submitted to a peer-reviewed journal in April.

As the study has not yet been published, this article is based on the information so far released from the Medical Research Council and Public Health England.

Most of the UK media’s reporting of the study is accurate. An exception to this is the headline from The Daily Telegraph – "HIV drug taken before and after sex cuts risk by 86pc", which is misleading as it implies that Truvada could be taken like a morning after pill, but this has not been tested.

It is highly likely that taking it in this manner would not be effective.


What kind of research was this?

This was a randomised controlled trial that aimed to see if Truvada was effective in reducing the incidence of HIV infection in gay and other MSM, and trans-women.

The use of drugs such as Truvada to prevent infection, rather than treat infection, is known as Pre-Exposure Prophylaxes (PrEP). Truvada is an anti-retroviral (anti-HIV) drug, which is usually used to treat HIV. It contains two antiviral compounds called emtricitabine and tenofovir disoproxil fumarate. The drug is taken once a day. Anti-retrovirals work by stopping the virus replicating in the body, allowing the immune system to repair itself and preventing further damage. They have proved very successful, though resistance can be a problem, so people with HIV are usually required to take a combination of drugs.

Truvada has already been shown to be effective in reducing the incidence of HIV infection compared to placebo (dummy pill). The purpose of this study was to see if taking Truvada changed sexual risk-taking behaviour, by making people feel that they were less likely to be infected and thus increasing their exposure to HIV.

This kind of research is important because among gay men, MSM, and trans-women in the UK the rate of HIV infection remains high at 2,800 in 2013.


What did the research involve?

The researchers recruited 545 gay men, MSM, and trans-women who were HIV negative into the PROUD study (Pre-exposure Option for reducing HIV in the UK: immediate or Deferred). The participants were randomly assigned to have Truvada immediately (N=276) or to wait and have it after 12 months (N=269).

The participants were recruited from 13 sexual health clinics in England between November 2012 and April 2014. People were eligible to be included in the study if they had reported having anal sex without a condom in the previous three months and planned to do so again in the near future. This put them in the very high risk category.

Participants in both groups were advised to continue other risk prevention strategies such as condom use. They were also asked to keep a short diary, fill out a monthly questionnaire and attend a clinic appointment every three months.


What were the basic results?

Those taking Truvada were 86% less likely to be infected with HIV:

  • HIV infection occurred in three people taking Truvada compared to 19 in the group who had to wait for a year.
  • The infection rate in the Truvada group was 1.3 people infected per 100 people followed up for one year (100 person-years).
  • The infection rate in the waiting group was 8.9 per 100 person-years.

Sexual risk-taking behaviour was judged not to have increased in the Truvada group as there was no difference between the groups in terms of the number of participants who had a sexually transmitted infection (STI).

No results were provided from the diaries or questionnaires.


How did the researchers interpret the results?

The chief investigator of the study, Sheena McCormack, is reported to have said: "These results are extremely exciting and show PrEP is highly effective at preventing HIV infection in the real world." They are now working with a range of stakeholders to determine whether a PrEP service could be commissioned across the NHS.



The results of this unpublished study were presented at a conference in Seattle and have been reported by the Medical Research Council, who helped fund it. As it has not been published, some important details are not yet known, such as:

  • The researchers report that there was "high adherence" to taking the medication, but it is not known how regularly it was taken, or how many people stopped taking it and why.
  • No details have been provided about any side effects experienced on the medication.
  • The incidence of STIs was used to determine whether taking Truvada changed sexual risk-taking behaviour. It is currently unclear which STIs were compared between the two groups. Three common STIs are viral (genital herpes, genital warts and human papilloma virus), so it is possible that the Truvada reduced their incidence in addition to HIV. This could be an added bonus, but we will need to await publication of the study to look at this.

A limitation of the study is the amount of contact the participants had with the sexual health clinics. They were asked to fill out monthly questionnaires and attend a clinic every three months. It is possible this frequent contact with services caused this particular group to be more aware of the risks of HIV infection.

The researchers plan to submit the study to a peer-reviewed journal in April. In the meantime, they are working with a range of stakeholders to determine whether a PrEP service could be commissioned across the NHS. It has been suggested that men may wish to take PrEP during periods in their life when their sexual risk is highest, rather than continuously. This will no doubt be among the many considerations that will be taken into account.

In conclusion, the researchers report that PrEP reduced HIV infection by 86% in this very high risk group when it was taken on a daily basis. Full publication of this study, and any further developments, are awaited.

The most effective method of reducing your risk of HIV if you are sexually active – and whether you are gay, bisexual, trans or straight, is to always use a condom.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Analysis by Bazian

Edited by NHS Choices


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Around 83,000 people in the UK are living with HIV. But according to Public Health England, more than a quarter don't know they have it