Can a Pill a Day Keep HIV Away?
In Combo With Safer Sex, Truvada Protects Gay/Bi Men From HIV Infection, Study Shows
"The iPrEx study is a very important addition to what is the most promising 15 months in the field of HIV prevention research since the epidemic began 27 years ago," says Alan Bernstein, MD, executive director of the Global HIV Vaccine Enterprise.
Bernstein notes that the iPrEx findings follow the news that a topical microbicide containing an AIDS drug can cut HIV infections in heterosexual women in Africa by 39% and the suggestion from a Thai trial that it's possible for a vaccine to prevent HIV (although the vaccine tested was itself not sufficiently effective).
PrEP Praise Comes With PrEP Warnings
Unfortunately, it takes more than a daily pill to prevent HIV infection. All of the experts who praised the iPrEx study were quick to warn that it's only one piece in the puzzle.
While the study showed that Truvada can protect gay and bisexual men, it can't be assumed that the same will hold true for heterosexual men and women, for couples in which only one member has HIV, or for intravenous drug users. Studies are under way to evaluate various PrEP formulations in these groups.
Truvada has not been approved by the FDA for prevention of HIV infection.
Fenton notes that PrEP cannot protect against STDs such as syphilis or chlamydia.
"It cannot be seen as the first line of defense against HIV," Fenton warns. "PrEP requires careful adherence, and is an intensive approach that won't be right for everyone. … Taking a daily pill is not as simple as it sounds."
In an editorial accompanying the Grant report in the Nov. 23 online edition of the New England Journal of Medicine, Walter Reed Army Institute researcher Nelson L. Michael, MD, PhD, notes the iPrEx study revealed several problems with PrEP:
- Men recently infected with HIV (and thus negative on a standard HIV test) developed drug-resistant HIV infections after starting PrEP.
- A small number of men showed signs of kidney dysfunction, a known side effect of Truvada. This means people taking the drug will have to be closely monitored.
- If so many men failed to take their Truvada every day during the strict confines of a clinical trial, what will happen in the real world?
- What will be the long-term safety of PrEP in people with health issues such as diabetes or high blood pressure?
- Will people taking PrEP forgo condom use, HIV testing, or other measures known to reduce HIV risk?