Postexposure prophylaxis of breastfeeding HIV-exposed infants with antiretroviral drugs to age 14 weeks: updated efficacy results of the PEPI-Malawi trial

BACKGROUND: This analysis updates and extends efficacy estimates of the PEPI-Malawi trial through age 24 months at study completion in September 2009. METHODS: Infants of breastfeeding HIV-infected women were randomized at birth to the following: (1) single-dose nevirapine (NVP) + 1-week zidovudine (ZDV) (control); (2) control + extended daily NVP (ExtNVP) through 14 weeks; (3) control + extended daily NVP + ZDV (ExtNVP/ZDV) through 14 weeks. We estimated rates of HIV infection death and HIV infection or death using Kaplan-Meier analysis. RESULTS: This analysis includes 3126 infants uninfected at birth as follows: 1004 control 1071 ExtNVP and 1051 ExtNVP/ZDV. By 9 months HIV infection rates were 5.0% in ExtNVP 6.0% in ExtNVP/ZDV and 11.1% in control (P < 0.001 comparing extended regimens with control). At age 24 months HIV infection rates had risen to ~11% in the extended arms compared with 15.6% in the controls (P < 0.05). The rates of HIV infection or death were also significantly lower in extended arms. There were no differences in severe adverse events with the exception of higher possibly related events in the ExtNVP/ZDV arm. CONCLUSIONS: Daily infant antiretroviral prophylaxis reduces postnatal HIV infection by ~70% during the period of prophylaxis. But continued HIV transmission after prophylaxis stops suggests more prolonged infant prophylaxis is needed.