Two Studies Show Daily Pill Can Reduce Risk of H.I.V. Infection

Two studies released on Wednesday have the potential to completely radicalize AIDS prevention.

According to these two studies, one of them performed by the Center for Disease Control and Prevention (CDC), ingesting a daily pill containing one or two AIDS drugs can save an uninfected individual from being infected by the fatal human immunodeficiency virus (HIV).

“This is an extremely exciting day for H.I.V. prevention,” said Dr. Kevin Fenton, director of AIDS prevention at the CDC in Atlanta.

Only a number of years ago, the only prevention methods against HIV were for individuals to use condoms during sexual activities or to abstain from sex altogether.

Recent research has proven other methods exist which can help decrease the risk of transmitting the infection, such as circumcision, vaginal microbicides, a daily pill for the uninfected (known as pre-exposure prophylaxis, or PrEP) and early treatment for the infected (known as “treatment as prevention”).

Partners PrEP is one of the two studies which were released Wednesday. It was performed in Kenya and Uganda on 4,758 “discordant couples” (couples in which one partner was infected and the other was not) by researchers from the University of Washington.

The results showed that study participants who ingested a daily Truvada pill, which is a concoction of tenofovir and emtricitabine, had a 73% lower chance of becoming infected. Uninfected individuals who were administered a Viread pill containing only tenofovir were 62% less likely of contracting the disease.

The second study, TDF2, was performed in Botswana by the CDC on 1,200 sexually active young adults. The researchers discovered that study participants who were administered Truvada had a 63% decreased chance of contracting the infection.

The results of both studies were meant to be released and presented at an AIDS conference in Rome next week, but after it became apparent that the pills were working effectively in the Partners PrEP study, the researchers ended early because it would be unethical to continue distributing placebos. The CDC released results from TDF2 simultaneously.

These results seem to confirm the promising release of the results from a breakthrough pre-exposure prophylaxis study, known as iPrEx, which was conducted among gay men in San Francisco. During the study, the male participants who ingested Truvada daily were 44% less likely to contract HIV, but the researchers reported that they analyzed blood samples from their subjects, and found that individuals whose blood samples proved they took the pill faithfully benefitted from 90% protection.

Blood samples are the best method of discovering whether study participants actually take their pills, and blood samples were drawn from participants in both recent studies, but since both were ended early, the samples have not been analyzed.

Currently, two more studies with similar objectives are being conducted, one on heterosexuals in Africa and one among drug users in Thailand.

“We don’t anticipate needing more,” reported Jonathan Mermin, a C.D.C. specialist in AIDS prevention.

As a result of the release of these promising findings, physicians may anticipate receiving requests from some heterosexual American patients for Truvada. According to Mermin, it will be several months before a new C.D.C. guideline can be written for the drug, but doctors may wish to use the guidelines written for the gay participants of the San Francisco study, as long as they keep in mind that Truvada has not been tested in pregnant women.

“It’s clear we’re not going to find a magic pill that prevents it,” stated Fenton, “but this is adding more to the tool kit.”