OBJECTIVES:

Single-dose nevirapine (SDNVP) for prevention of mother-to-child HIV transmission selects mutations conferring resistance to nonnucleoside reverse transcriptase inhibitor (NNRTI)-based therapy. We investigated mortality and virologic and clinical outcomes after introduction of antiretroviral treatment (ART) among a cohort of women given SDNVP.

METHODS:

When ART programs were introduced in 2004 in Lusaka, Zambia, we were completing a trial of infant feeding, which involved following HIV-infected women who received SDNVP between 2001 and 2005. Women still in follow-up or who could be contacted were evaluated for eligibility for ART (CD4 count <200 or <350 and World Health Organization stage >or=3) and started on NNRTI-based therapy if eligible. We compared mortality in the cohort of women before and after ART access, and examined, among women initiating ART, whether virologic response was better allowing a longer time to elapse between SDNVP and treatment initiation.

RESULTS:

In the cohort of 872 women, mortality more than halved after ART became available (relative hazard = 0.46, 95% confidence interval: 0.23 to 0.91, P = 0.03). Of 161 SDNVP-exposed women followed on NNRTI-based ART, 70.8% suppressed (viral load <400 copies/mL). Only 3 of 8 SDNVP-exposed women (37.5%) <6 months of starting therapy suppressed compared with 13 of 22 (59.1%) who started 6-12 months, 44 of 61 (72.1%) 12-24 months, and 54 of 70 (77.1%) >24 months after exposure (chi2 trend P = 0.01).

CONCLUSIONS:

Most SDNVP-exposed women respond well to NNRTI-based therapy, but there was an attenuation of therapy efficacy that persisted to 12 months after exposure. Women should be screened for ART eligibility during pregnancy and started on effective regimens before delivery.