Short course of AZT halves HIV-1 perinatal transmission

The ACTG 076 trial assessed the ability of zidovudine (AZT) to prevent the transmission of HIV from mother to child. In that trial, women received 100 mg of AZT 5 times daily beginning from 14-34 gestational weeks, then intravenous AZT during labor. This approach, followed by the administration of AZT to infants for 6 weeks, led to an 8% mother-to-child HIV transmission rate compared to 23% with placebo. Drug therapy proven in the ACTG 076 trial has now become the basis for current practice in developed countries. Placebo-controlled clinical trials were later launched in selected developing countries to assess the effect upon vertical transmission of providing only a short course of AZT therapy to HIV-infected mothers. In Thailand, 397 HIV-infected pregnant women were randomized to take orally either placebo or 300 mg of AZT twice daily from 36 weeks of gestation, then 300 mg every 3 hours during labor. Infants did not receive AZT and the women did not breast-feed. Kaplan-Meier analysis found a perinatal HIV-1 transmission rate of 18.6% in the placebo group and 9.2% in the treatment group. Based upon these preliminary data, the US Centers for Disease Control and Prevention (CDC), who collaborated with the Thai Ministry of Public Health in the study, announced on February 18 that all women in the CDC's Cote d'Ivoire collaboration will now receive active AZT treatment. Use of a placebo group in the Cote d'Ivoire study helped to identify the effect of the country's limited obstetric services upon neonatal mortality. UNAIDS is hosting an international meeting in March to find ways of rapidly and effectively implementing these and other data. In future perinatal trials, placebo arms should either be dropped or replaced with the CDC short-course regimen.