Transmission rates in consecutive pregnancies exposed to single-dose Nevirapine in Soweto, South Africa and Abidjan, Cote d'Ivoire

Background: Large numbers of women receive single-dose nevirapine (sdNVP) to prevent mother-to-child transmission (MTCT) of HIV; over time, an increasing proportion will return to prevention of MTCT programs for a second pregnancy. Because sdNVP selects resistance in a high percentage of women, we compared the effectiveness of sdNVP in preventing peripartum MTCT in successive pregnancies. Methods: Prospective cohorts were recruited from MTCT programs in South Africa and Cote d'Ivoire. HIV-1-infected women and their infants exposed to sdN`VP in 2 consecutive pregnancies-used alone or with zidovudine (ZDV) or ZDV plus lamivudine-were included. Results: The median age of women at their initial exposure to sdNVP in Soweto (n = 120) and Abidjan (n = 41) was 26 (interquartile range [IQR]: 22-29) years and 28 (IQR: 24-31) years, respectively, and their median delivery interval was 21 (IQR: 15 29) months and 26 (IQR: 20-32) months, respectively. Transmission rates in Soweto and in Abidjan were 11.1% and 13.2% for the first pregnancy and 11.1% and 5.4% for the second pregnancy (P = 1.000 and P = 0.449 for Soweto and Abidjan, respectively, in impaired analysis). Conclusion: This analysis suggests that the effectiveness of sdNVP when used in successive pregnancies is probably not impaired, possibly because viral resistance selected by prior exposure to sdNVP may wane with time.