We don’t have a vaccine, and we have yet to find a cure. Yet despite these setbacks, HIV eradication is still possible with the means that we currently have. Antiviral drugs lower the amount of virus in bodily fluids to such an extent that the risk of transmission is virtually eliminated. Condoms are almost 100 percent effective. And antimicrobial drug-loaded lubricants can make them even safer. We have this strong armamentarium, but we don’t have adherence. Could the HIV “morning after pill” help or hinder this situation?
The pill we’re referring to is Truvada, a combination of two antiviral drugs that target different stages of the HIV lifecycle, an approach that reduces the likelihood of resistance developing. It was originally developed as a treatment for those already infected, but it was also used as a so-called “post-exposure prophylaxis” (PEP) to prevent those who have or could have been exposed to HIV from becoming infected. It’s extremely effective at doing so, provided it’s given within 72 hours but ideally much sooner than that.
But a few years back, the potential of using this same drug as a preventive measure pre-exposure was realized, and the FDA licensed it for such use in 2012. This was the first drug approved to reduce the risk of acquiring HIV in high-risk, uninfected individuals. Numerous trials have since been carried out, most of which have sung the drug’s praise. For example, the PROUD study, the U.K.’s first trial of Truvada as "pre-exposure prophylaxis" (PrEP), found that taking it daily reduced the risk of infection by 86 percent in sexually active gay men, when compared with a placebo.
But if it’s so effective, why did it not bestow 100 percent protection? Out of a total of 544 participants, three men in the PrEP group were infected with HIV, compared with 20 taking the dummy pills. It’s thought that one in the former group may have been infected prior to the trial, and that the other two did not adhere to their regimen as they did not pick up all of their prescriptions.
Image credit: If you take PrEP, you should still use condoms. wasa_d/Shutterstock
Studies of injecting-drug users and heterosexuals also found that, when the drug was adhered to, it provided a high level of protection. Bucking the trend, though, two trials on women in Africa found that PrEP did not reduce HIV infections, but once again this was attributed to participants not taking their drugs as required. So if it’s too hard to stick to a daily regimen, as evidenced by these trials, is PrEP really worth the money, costing up to $830 (£550) per person annually? A new trial, called IPERGAY, suggests so.
Conducted in France and Canada, the trial looked at the effectiveness of Truvada when taken as needed, as opposed to daily, in heterosexual men and transgender women. The idea was that adherence might be higher when the drug doesn’t need to be taken every day. Alongside being provided with counselling and condoms, those in the PrEP group were instructed to take two pills before sex, one a day later, and a third 24 hours after that. Mirroring the PROUD study, and once again highlighting its usefulness, it was found that those taking Truvada were 86 percent less likely to become infected with HIV than those taking a placebo. These findings have been published in the New England Journal of Medicine.
It’s clear Truvada has a place in our fight against HIV; even the CDC now recommends it should be used by around 1 in 4 sexually active gay and bisexual men, and 1 in 5 injecting-drug users. So why is there hesitation? It’s been argued that taking PrEP might give the illusion of invincibility against the STI, and thus increase the likelihood that people will engage in risky activities, perhaps forgoing condom use when they ordinarily would not.
But in general, studies don’t support this notion. In IPERGAY, for instance, sexual practices were not found to change throughout the study period, and during PROUD there were no other STIs diagnosed in the PrEP group. That said, a trial in the U.S. found that some participants decided to use PrEP as their sole defense, although most of those tended not to use condoms before the trial began anyway.
Truvada has the potential to really make a dent in new HIV infections, provided it’s offered with sexual health counselling and condoms are made available. And the quicker it is rolled out en masse to those who need it, the quicker we will start to see benefits from its use.