Postnatal HIV-1 Transmission after Cessation of Infant Extended Antiretroviral Prophylaxis and Effect of Maternal Highly Active Antiretroviral Therapy

Background. The association between postnatal human immunodeficiency virus type 1 (HIV-1) transmission and maternal highly active antiretroviral therapy (HAART) after infant extended antiretroviral prophylaxis was assessed. Methods. A follow-up study was conducted for the Post-Exposure Prophylaxis of Infants trial in Blantyre, Malawi (PEPI-Malawi). In PEPI-Malawi, breast-feeding infants of HIV-infected women were randomized at birth to receive a either control regimen (single-dose nevirapine plus 1 week of zidovudine); the control regimen plus nevirapine to age 14 weeks; or the control regimen plus nevirapine and zidovudine to age 14 weeks. Infant HIV infection, maternal CD4 cell count, and HAART use were determined. Maternal HAART use was categorized as HAART eligible but untreated (CD4 cell count of <250 cells/mu L, no HAART received), HAART eligible and treated (CD4 cell count of <250 cells/mu L, HAART received), and HAART ineligible (CD4 cell count of >= 250 cells/mu L). The incidence of HIV infection and the association between postnatal HIV transmission and maternal HAART were calculated among infants who were HIV negative at 14 weeks. Results. Of 2318 infants, 130 (5.6%) acquired HIV infection, and 310 mothers (13.4%) received HAART. The rates of HIV transmission (in cases per 100 person-years) were as follows: for the HAART-eligible/untreated category, 10.56 (95% confidence interval [CI], 7.91-13.82); for the HAART-eligible/treated category, 1.79 (95% CI, 0.58-4.18); and for the HAART-ineligible category, 3.66 (95% CI, 2.86-4.61). The HIV transmission rate ratio for the HAART-eligible/treated category versus the HAART-eligible/untreated category, adjusted for infant prophylaxis, was 0.18 (95% CI, 0.07-0.44). Conclusions. Postnatal HIV transmission continues after cessation of infant prophylaxis. HAART-eligible women should start treatment early for their own health and to reduce postnatal HIV transmission to their infants.