Late postnatal transmission of HIV-1 and associated factors

Background. The present study was undertaken to determine the risk and timing of late postnatal transmission ( LPT) of human immunodeficiency virus type 1 ( HIV-1). Methods. Breast-fed infants previously enrolled in 2 trials of antiretroviral prophylaxis were monitored in Malawi. Kaplan-Meier and proportional hazard models assessed cumulative incidence and association of factors with LPT. Results. Overall, 98 infants were HIV infected, and 1158 were uninfected. The cumulative risk of LPT at age 24 months was 9.68% ( 95% confidence interval, 7.80%-11.56%). The interval hazards at 1.5-6, 6-12, 12-18, and 18-24 months were 1.22%, 4.05%, 3.48%, and 1.27%, respectively. Conclusions. The risk of LPT beyond 6 months is substantial. Weaning at 6 months could prevent 185% of LPT.