In 2012, PrEP (or pre-exposure prophylaxis) was approved in the United States for the prevention of HIV. This once-daily oral pill dramatically reduces the odds of contracting HIV by making it very difficult for the virus to take hold in the body (watch this video to learn more about how it works).
Several studies have found that PrEP reduces the risk of contracting HIV by 90 percent or more. The drug is most effective when taken every day, with some research suggesting that it may be closer to 100 percent effective when taken consistently. In addition, it has few side effects, and—while expensive—it's cost-effective from a public health standpoint, meaning it's cheaper to prevent a bunch of HIV infections than it is to treat them. And it's only going to become more cost-effective now that the FDA has approved a generic version of the drug.
The downside to PrEP, though, is that it's only designed to offer protection against HIV, so those who take the drug still need to use condoms in order to prevent other sexually transmitted infections (STIs). However, if HIV is the most feared STI and PrEP allays people's concerns about contracting it, is it possible that getting on PrEP might stop people from using condoms altogether? Scientists have been curious about the answer to this question ever since PrEP was approved for use—and here's what they've learned.
Before we get to the results, I should mention that virtually all of the studies looking at whether PrEP users compensate for their lower HIV risk by dropping condoms have focused on gay and bisexual men because, in the United States, they're the group that's most at-risk for HIV—and therefore most likely to use PrEP. So, we're really only going to be talking about men who have sex with men here.
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With that said, early clinical trials painted a pretty consistent picture: men didn't report an increase in condomless sex after beginning PrEP. In fact, some studies reported decreases in risky sexual behavior. In other words, it didn't seem to be the case that gay and bisexual men were engaging in any kind of risk compensation. If anything, more safe sex was taking place.
However, it's important to be cautious about generalizing these results to the real world because in those early clinical trials of PrEP, no one really knew that much about the drug or its effectiveness. As result, participants may have acted more cautiously. By contrast, now that PrEP has been heavily advertised as an extremely effective HIV-prevention tool and many gay and bisexual men have friends who are taking it, there's probably a lot less skepticism and a lot more confidence in the drug.
This may explain why, in part, I've now seen three studies from three different countries (the US, the Netherlands, and Australia) emerge since the beginning of this year reporting effects opposite of those initial trials. Specifically, all three of these studies found that PrEP users engaged in more condomless sex in the months after starting the drug.
Of course, we can't say exactly what accounts for the fact that newer studies are reporting results that are inconsistent with older studies. It could be, as I suggested, due to changes in perceptions of PrEP. However, it could also be that what we're seeing here is that PrEP just affects different people in different ways. For example, the act of taking a daily pill may serve as a constant reminder to some people about the fact that sex carries certain risks, which may—in turn—lead them to practice safer sex. By contrast, others may find that PrEP relieves anxiety and fear, which gives them a sense of freedom or invulnerability that ultimately reduces condom use.
Nonetheless, what the new studies tell us is that PrEP does seem to be pushing at least some (but certainly not all) gay and bisexual men to use condoms less often. However, this doesn't necessarily mean that PrEP is a bad thing or that doctors should stop prescribing it out of fear that their patients will engage in risk compensation.
For one thing, scientists believe that even if some degree of risk compensation occurs, it won't undermine the preventative impact of PrEP on the spread of HIV. Indeed, in a new study that employed mathematical modeling, researchers concluded that even if condom use declines following initiation of PrEP, we are still likely to see a dramatic reduction in HIV rates overall, which is ultimately a very good thing.
In other words, even if some PrEP users start using condoms less, there's still a net public health benefit to be had. This is an important point for physicians to keep in mind. Some doctors are concerned about prescribing PrEP to gay and bisexual men precisely because they are afraid it will encourage more condomless sex. However, even if PrEP does mean less condom use in some cases, this does not necessarily outweigh the protective benefit.
That said, the fact that PrEP does seem to change some gay and bisexual men's condom use habits is a sign that we need more education about the risks of other STIs, especially now that we're in the era of antibiotic-resistant gonorrhea. Remember that PrEP was never designed to be a replacement for condoms, but rather a way to augment the protection they offer.
Justin Lehmiller is the director of the social psychology program at Ball State University, a faculty affiliate of The Kinsey Institute, and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller.
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Correction (8/24/2017): A previous version of this article stated that PrEP was approved in the US in 2014. It was actually approved in 2012—2014 was when the CDC amended its guidelines to start recommending the treatment.