A recent study performed by Kaiser Permanente of San Francisco has helped show the effectiveness of a daily regimen of Truvada in the prevention against HIV infection. After monitoring 657 of its clients who were on PrEP over a two year period, the insurer announced that none of the subjects had contracted the virus, reports The New York Times.
The study began shortly after the F.D.A. approved the use of Truvada for HIV prevention in mid-2012 and was completed in February of this year. Dr. Jonathan E. Volk, an epidemiologist for Kaiser Permanente of San Francisco, and his colleagues monitored a group of men who engaged in risky sexual behavior. While the men used fewer condoms during this time period, none of them became HIV-positive.
“This is very reassuring data,” Dr. Jonathan E. Volk stated. “It tells us that PrEP works even in a high-risk population.”
It’s worth noting that Kaiser’s data is based on an observational study, which is not as scientifically monitored to the same degree as clinical trials. For example, Dr. Volk stated they did not take blood samples from the clients to see if they were taking Truvada regularly. The researchers were operating under the assumption that since the men requested to be on PrEP they were taking it as directed by their primary physicians. Clinical trials on Truvada have been done in the past, but since these studies usually utilize placebos, they were halted once researchers decided it was unethical to keep some participants on placebos after PrEP’s effectiveness was proven.
All but four of the participants in the Kaiser study were gay men, and 84 percent of them reported sexual activity with multiple partners. After six months of being on PrEP, 143 of the subjects were asked about their sexual behavior. More than 40 percent of them stated they were using condoms less, and 74 percent of that group said that their number of sexual partners had not changed.
However, don’t go throwing out your supply of condoms just yet. Even though there were no new HIV infections among the group, half of the 657 participants became infected with syphilis, gonorrhea or chlamydia within the first year. Dr. Volk observed that the “rates of those infections had begun climbing among gay men even before PrEP became available” since some men began to engage in the practice of serosorting — engaging in condomless sex only with men of the same HIV status as themselves. He also noted that HIV-negative men who agreed to condomless sex with positive men who were undetectable due to a regimen of antiretroviral drugs were also at risk of an increased exposure to STIs as well.