A shorter postnatal course of zidovudine (AZT) for the infants of HIV-positive mothers may be as effective at preventing vertical HIV transmission as the current regimen, a recent study suggests.

Current recommendations call for the mother to start AZT at 28 weeks' gestation and the infant to receive it for six weeks after birth. Yet this study shows that vertical transmission rates didn't increase when the infant stopped receiving AZT three days after birth, as long as the mother began taking the drug at 28 weeks' gestation. Infants of women who started taking the drug later, at 35 weeks' gestation, did need to continue receiving AZT for six weeks after birth to minimize the risk of transmission; even so, vertical transmission rates were higher for these infants.

These results could be especially important to developing nations, in which inadequate resources and drug supplies prevent the administration of extended treatment regimens.

Lallemant M, et al. N Engl J Med 2000;343(14):982-91.