A single dose of nevirapine for both the mother and newborn infant lowers the rate of mother-to-child transmission of HIV-1 by more than 40%. Nevertheless, large numbers of both women and infants become resistant to nevirapine when exposed to a single peripartum dose. This prospective observational study was done to assess virologic responses to nevirapine-based antiretroviral treatment in women and infants who had previously been randomly assigned to receive a single peripartum dose of nevirapine or placebo. The major end point for both mothers and infants was virologic failure at the 6-month follow-up visit after initiation of antiretroviral therapy. Of 218 women who began antiretroviral therapy, 112 had received a single dose of nevirapine, and 106, placebo.
Rates of virologic failure 6 months after the start of antiretroviral treatment were 5% for placebo recipients and 18% for those given a single dose of nevirapine. Among 60 women who began antiretroviral treatment within 6 months of randomization, 42% of those given nevirapine but none of the placebo recipients were virologic failures. In contrast, no significant difference in failure rates were noted in women who began antiretroviral treatment 6 months or more postpartum. Among 30 infants placed on antiretroviral therapy, virologic failure after 6 months was significantly more frequent in those given a single dose of nevirapine than in placebo recipients (P < 0.001). On multivariate analysis stratified according to the timing of initial antiretroviral treatment, baseline counts of CD4+ cells and a single dose of nevirapine, but not the plasma level of HIV-1 RNA, were significantly associated with the time to virologic failure.
Where possible, women who qualify for combination antiretroviral treatment on their own account should receive it. They not only are the women at highest risk of AIDS-related complications or death, but also are the likeliest to transmit infection to their infants. For women who do not yet qualify for antiretroviral treatment or where treatment is not available, prophylactic single dose of nevirapine—with or without other antiretroviral agents—remains an important way of preventing mother-to-child transmission of HIV-1 infection. Women exposed more remotely to a single dose of nevirapine have high rates of viral suppression when receiving nevirapine-based antiretroviral therapy.