WASHINGTON — Treating HIV right away, before patients are too sick, dramatically lowers their chances of spreading the AIDS virus to a sexual partner, says a major international study that may convince more doctors to offer medication sooner.
The nine-nation study offers convincing evidence of what scientists have long believed — that HIV medicines don't just benefit the patient, but may act as a preventive by making those people less infectious. Earlier treatment in the study meant patients were 96 percent less likely to spread the virus to their uninfected partners, according to preliminary results announced Thursday by the National Institutes of Health, which oversaw the research.
Those findings were striking enough that the NIH said it was stopping the study four years ahead of schedule to get the word out.
When HIV patients should start taking antiviral drugs is an important question. The pills are lifesaving but also expensive — up to $15,000 a year in the U.S. —and carry a range of side effects including diarrhea and liver damage.
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Anthony Fauci of the NIH said the new study promises to change practice worldwide. In developing countries, where the drugs cost a few hundred dollars a year, patients tend to be far sicker before getting medication. Even in the U.S., where therapy starts sooner, doctors don't always treat as early as was done in this study.
"It has less to do with a decision about what's good for you from a personal health standpoint than what is the extra added benefit from starting earlier, i.e., transmission, especially if you have a partner who's uninfected," said Fauci, director of the National Institute of Allergy and Infectious Diseases.
Condoms remain crucial for protection — the medications don't change that longtime recommendation. All 1,763 couples in the study, where one partner had HIV and the other didn't, were urged to use them.
"HIV-positive people cannot assume they are not infectious simply because they are already on treatment medications," warned Thomas Frieden, director of the Centers for Disease Control and Prevention.
Previous research has suggested that HIV patients who use the medications are less likely to spread infection. But the $73 million study announced Thursday is the first to rigorously test that.
The earlier treatment also helped reduce some complications — such as a form of tuberculosis — in the original patients, but there was no significant difference in deaths between the two groups.
The study included couples from Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, Zimbabwe, as well as a few from the United States.