HIV Prevention: Drugs Even More Effective Than Thought

The early initiation of antiretroviral therapy reduces rates of heterosexually transmitted HIV even more than previously reported, investigators announced Monday at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Rome. Early ART is also associated with a 41 percent reduction in HIV-related morbidity and mortality, they said.

In the HPTN 052 trial -- conducted in nine countries, including the United States -- HIV-infected partners in 1,763 serodiscordant couples were randomized to initiate ART either immediately or to delay treatment until their CD4 cell count was 250 cells per microliter.

Researchers announced in May that monitors stopped the trial ahead of schedule upon finding that immediate ART for the infected partner provided a 96 percent reduction in HIV transmission. However, the protective effect "may be even be even stronger than initially reported," said investigators presenting new, peer-reviewed data at the conference.

A triple test initially confirmed 27 transmissions among couples in the delayed-treatment group, compared with just one in the immediate-treatment group. According to data presented in Rome, investigators discovered one additional transmission had occurred in the delayed-treatment group before the trial was halted. The lone infection in the immediate-treatment arm likely was in a patient who had acquired it so recently that ARVs were not as effective in suppressing virus in bodily fluids.

"The protection is going to be greater than 96 percent," said trial leader Dr. Myron Cohen of the University of North Carolina-Chapel Hill.

Attendees stood and cheered as researchers announced the findings.

The World Health Organization says it will delay planned revisions to its treatment guidelines in order to take into account "the exciting results." Even in light of the new research, however, condom use remains a key message for prevention, said Gottfried Hirnschall, director of WHO's HIV/AIDS department.

The study, "Prevention of HIV-1 Infection with Early Antiretroviral Therapy," was published ahead of the print edition of the New England Journal of Medicine (2011;doi:10.1056/NEJMoa1105243).

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