Preparing to Prevent HIV

Peter Watts reports

There is the view that condoms don’t take a lot of effort or preparation to use. They do. Although condoms offer optimal and traditional prevention against HIV, over time the proportion of gay men reporting condom-less anal sex has increased1 – to 61% (among those with a regular partner) or 41% (among those with casual partners). HPTO Blog 17.03.15 shutterstock_66087451Acceptability and choice, along with the degree of control in all situations, as well as fluctuating use of condoms, are likely to be involved and these issues can affect other people at risk of HIV as well.

HIV treatments may be difficult to take always too, but they offer new ways to think about added prevention. Whilst studies on HIV treatment among HIV-positive people show strong evidence for its use as an effective prevention method (in the presence of undetectable viral load), other studies among HIV-negative people using a particular HIV treatment Truvada (1 pill containing 2 drugs) are showing us how successful prevention can be when combination methods are shared among everyone!…What’s more, is that these studies, don’t show a further decline in condom use as a result of taking pre-exposure prophylaxis (PrEP) treatment. PrEP is not required right in the very moment of sex (like condoms are) as it is taken before and after sex (as prescribed by a doctor) and so the drug levels in the bloodstream are providing its protection against HIV in the body. PrEP can be an added safeguard for people who find condoms difficult to use all the time, although the studies encourage and support continued condom use.

PrEP is for people who may be at high risk of HIV infection, and so can be beneficial in sero-discordant relationships – especially where the HIV-positive partner is not on treatment or with a detectable viral load, or when a heterosexual serodiscordant couple is seeking to naturally conceive a child (although this would require additional medical advice for the safety of the foetus to drug exposure). The Partners PrEP study2 (conducted in Uganda & Kenya – reported at CROI 20153) provided a clear example that PrEP can act as ‘a bridge’ for prevention for the HIV-negative partner, while their HIV-positive partner starts treatment to commence bringing their viral load down. This study model showed that the combined approach – both partners started on treatment (PrEP & ART) – was 96% protective. This matches the 96% reduction in transmission risk previously seen in the HPTN052 study (although that study did not include PrEP: HIV-positive partner on treatment only).

Two other important and significant studies of PrEP among gay men were reported at CROI 2015: PROUD (UK) and IPERGAY (French/Canadian):

The PROUD study4 enrolled more than 500 gay men at higher risk of HIV infection. Half of the participants were given a daily pill of Truvada, the other half were deferred for one year before starting PrEP. The people taking a daily pill of tenofovir and emtricitabine (Truvada) were 86% less likely to get HIV than the people in the deferred group.

The IPERGAY study5 enrolled more than 400 participants. Half of the participants were asked to take four tablets of tenofovir and emtricitabine (Truvada), two before and two after sexual intercourse; the other half were given a placebo. People in the group taking the active pill before and after sex were 86% less likely to get HIV.

In comparing different study dosing frequencies, daily oral PrEP has been seen to provide the highest protection, but results from studies such as IPERGAY suggest that on-demand dosing (before and after condom-less sex) may provide enough protection, given that IPERGAY also found (as did PROUD) 86% protection against HIV.

Both these studies are continuing as single arm studies. In the PROUD study everyone is now taking active PrEP (rather than waiting). Also, in IPERGAY everyone now is taking the active study drug (not placebo). The first year preliminary results of both studies are highly encouraging.

These studies also help us reflect upon the significant value of combining strategies of treatment among HIV-negative people and HIV-positive people. Together, Pre-exposure Prophylaxis (PrEP) among HIV-negative people, and Antiretroviral Treatment (ART) among HIV-positive people (which brings the viral load down low), and tied to other negotiated safety strategies, are stepping up to pave the way to the virtual elimination of new HIV infections. Now, more than ever – with access programs becoming available for PrEP, and the expansion of treatment access for HIV-positive people who may opt for treatment at any time point (such as Australia where the CD4 count threshold has been lifted) – eliminating HIV transmissions is now truly a shared responsibility and opportunity among all people.

Recommended Further Reading:

References:

  1. Lee, E., Mao, L., Atkinson, C., Brown, S., Warner, M., Heywood, J., Prestage, G., Zablotska, I., de Wit, J., & Holt, M. (2014). Gay Community Periodic Survey: Queensland 2014. Sydney: Centre for Social Research in Health, UNSW Australia. https://csrh.arts.unsw.edu.au/media/CSRHFile/GCPS_Queensland_2014_web_FINAL.pdf
  2. Partners PrEP Study: Gus Cairn 26th February 2015. aidsmap.com/Combining-PrEP-and-ART-could-almost-eliminate-HIV-infection-east-African-study-finds/page/2948836/
  3. Conference of Retroviruses and Opportunistics Infections (CROI) 2105. croiconference.org/
  4. PROUD study: Gus Cairns, 24th February, 2015 aidsmap.com/Pre-exposure-prophylaxis-PrEP-stops-86-of-HIV-infections-in-PROUD-study/page/2947319/
  5. IPERGAY Study: Gus Cairns 24th February 2015. aidsmap.com/Pre-exposure-prophylaxis-also-stops-86-of-HIV-infections-in-Ipergay-study/page/2947854/
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