Two doses of PrEP before sex and one tablet every day for 48 hours works just as well as everyday use in gay men and other men who have sex with men.
Two doses of PrEP before sex and one tablet every day for 48 hours works just as well as everyday use in gay men and other men who have sex with men.

Gay men can now confidently take the HIV prevention pill before and for two days after sex — instead of daily doses — without compromising their protection against the virus, Anova senior clinical specialist Kevin Rebe says. 

The HIV prevention pill combines two antiretroviral drugs, Tenofovir and Emtricitabine. Studies over the past decade have shown that taking the tablet as pre-exposure prophylaxis (PrEP) can drastically reduce someone’s chances of contracting HIV sexually by up to 96% — if taken daily.

But recently two major studies confirmed that two doses of the drug before sex and one tablet every day for 48 hours — or what’s known as “PrEP on demand” — works just as well as everyday use in gay men and other men who have sex with men. The easier-to-use method has also been called “2-1-1” dosing. 


2-1-1. That’s the new phrase that pays for gay men looking to stay safe during sex. (John McCain)

In June, French researchers revealed that not a single man using PrEP on demand for a year had contracted HIV despite having regular unprotected sex. The men were part of more than 1 400 men who have sex with men who were given a choice between using the HIV prevention pill daily or using PrEP when they needed it, research presented at the 2018 international Aids conference shows. 

The study followed 2015 research published in the New England Journal of Medicine and conducted among more than 400 Canadian and French men who have sex with men that showed PrEP on demand worked

South Africa’s current PrEP guidelines were drafted before the most recent research and therefore do not include on-demand PrEP, Rebe explains. 

Medical associations in EuropeAustralia and Canada — for example — have already endorsed PrEP on demand as an alternative to daily doses of the HIV prevention pill.

But Rebe cautions that there is no evidence that PrEP on demand works for women, who typically need more of the drug more often than men to achieve the same effect. That’s because the tablet’s ability to ward off HIV infection depends on how much of it a person can build up in their bloodstream and tissues in the areas where HIV first enters the body — the rectum or the vagina. 

If levels are high enough in these areas, PrEP can stop HIV infections from taking hold there most of the time. 

Historically, studies into PrEP in women have shown worse results than those in men and this has mostly been blamed on women’s difficulties in taking the pill every day at the same time. But researchers are increasingly discovering that common germs in some women’s vaginas may affect how well PrEP works for them, according to 2017 research published in the journal Science. Also, it appears that women may need higher levels of adherence, or correct use of PrEP, compared with men.

PrEP on demand may also not currently be recommended for transgender women taking the gender-aligning hormone oestrogen. 

At the recent international Aids conference, scientists presented the results of a small study among 20 transgender women who were on both oestrogen and daily PrEP.

Although the study found that taking both medications together didn’t affect the level of oestrogen in women’s bodies, it did decrease the amount of PrEP in their blood although scientists didn’t test rectal levels specifically. 

Researcher Akarin Hiransuthikul told Bhekisisa that more research is needed to figure out what this means for transgender women and the HIV prevention pill.

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