A yearlong ethical controversy over AIDS clinical trials seemed headed toward a resolution today, as the U.S. government unveiled data from Thailand showing that short-term therapy with the antiviral drug AZT cut in half the rate at which HIV, the AIDS virus, is transmitted from mother to child at birth. This finding was released by the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, which sponsored the trial in Thailand.
The findings suggest it may be possible to reduce the rate of HIV infection among babies in poor countries with an inexpensive version of the more elaborate AZT therapy currently used in the United States and Europe. "This is very important," says epidemiologist Ken Nelson of the Johns Hopkins University in Baltimore: "It means that the possibility of delivering this kind of therapy" in the developing world "is becoming real."
The news from Thailand may also bring relief of another kind--ending an emotional debate that has been raging in the public health community. Critics, led by Sidney Wolfe of Ralph Nader's Public Citizen Inc. in Washington, D.C., have attacked CDC-sponsored studies in Thailand and in Africa because some participants were given only a placebo while others received AZT. Because long-term AZT treatment is known to cut transmission rates in the United States and Europe, Wolfe argued, it is unethical to withhold such treatment from study participants in the developing world. Researchers designed the protocols this way, however, because they feared that the effects of short-term AZT therapy might be obscured unless they were compared directly with findings from an untreated group.
That debate is now moot. According to CDC official Phillip Nieburg, the Thai data show that HIV-positive pregnant women who got a daily dose of AZT for just 3 to 4 weeks before giving birth were far less likely to transmit the deadly virus to their child than were those who received no drug. The virus transmission rate for women who received AZT was 9.2%, according to CDC, compared with 18.6% for the placebo group. For that reason, Nieburg says, the CDC has decided that placebos should no longer be used in these trials, and the Thai researchers have agreed not to enroll any more women in the placebo group. Nieburg confirms that leaders of other AZT studies sponsored by the United States, the United Nations, and France also have decided to drop placebos.