STUDY: PrEP is Still Pretty Effective When Taken Less Than Daily—But is it Enough?

The results of the recent French IPERGAY study on Truvada as pre-exposure prophylaxis, or PrEP as it is most commonly referred to, were made available to the public this week and proved what many experts have long believed about the much-debated treatment. Taken correctly, PrEP is very effective in the fight to prevent HIV and it may continue to protect users even when taken at levels different than what is currently prescribed.

At the 2015 Conference on Retroviruses and Opportunistic Infections in Seattle, ANRS (Agence Nationale de Recherche sur le Sida et les hepatites virales, the French research agency that conducted the IPERGAY trials) tested a PrEP regimen that included taking the pill a few days before and after sexual encounters, as opposed to the recommended daily usage that is currently approved by the US Food & Drug Administration.

Researchers announced that that the shortened dosage reduced the risk of HIV in gay and bi men by an average of over 86 percent. But don’t think that means it’s an on-demand drug, or a before and after pill, as was previously reported in the media last year.

Currently PrEP is only approved for daily use, and if taken as studied in the IPERGAY and PROUD trials some experts warn users could be putting themselves at risk for contracting HIV.

“We don’t want people to potentially put their lives at risk from taking the wrong kind of PrEP regimen,” said Jennifer Horvath, deputy director of news media at the Centers for Disease Control and Prevention. Horvath also stresses that PrEP is used in IPERGAY after sex, it is not to be confused with post-exposure prophylaxis, or PEP, which is a type of medication you must take within 72 hours and for 28 days after one has potentially been exposed to HIV.

According to a statement by the CDC, during the IPERGAY study, over 400 enrolled participants took a dose of two pills between two to 24 hours before they were planning on having sex, and another two pills 24 to 48 after the last pre-sex dose. This type of occasional medication schedule was used per each sexual encounter to test the effectiveness of an infrequent PrEP regimen.

“The IPERGAY trial provides the first evidence that an event-driven regimen is effective among high-risk MSM with frequent sex,” said Dr. Jonathan Mermin, director of the CDC’s Nation Center for HIV/Aids Prevention, in a statement.

In a separate U.K.-based study called PROUD, researchers at the U.K. Medical Research Council also found PrEP results that were just as efficient as the ones found in IPERGAY, with an 86 percent rate of lowered HIV risk in those participating in the study.

Mermin says it's worth noting that it isn’t known whether or not PrEP will be effective if only taken a few hours (or even days) before unprotected sex. He states that it may take days for PrEP drugs to reach the best levels of medication in the body that are needed to prevent infection.

The 86 percent rate of lowered HIV risk on an intermittent regimen was found using IPERGAY’s placebo controlled trial (random participants were given the PrEP drugs and others were given a a placebo). That lowered risk is significantly lower than the 94 percent effectiveness rate when taken daily, as previously reported.

Despite the caveat, many activists and health care workers welcomed the results of the IPERGAY and PROUD studies as experts work to bring down still escalating rates of HIV among gay and bi men.

“Fantastic results on #HIV pre-exposure prophylaxis (#PrEP) coming out of the #CROI conference in the US,” activist Paul Kidd tweeted. “We can end this epidemic.”

For more facts on PrEP, click here.