INTERNATIONAL MULTICENTER POOLED ANALYSIS OF LATE POSTNATAL MOTHER-TO-CHILD TRANSMISSION OF HIV-1 INFECTION

Background An understanding of the risk and timing of mother-to-child transmission of HIV-1 in the postnatal period is important for the dev elopment of public-health strategies. We aimed to estimate the rate an d timing of late postnatal transmission of HIV-1. Methods We did an in ternational multicentre pooled analysis of individual data from prospe ctive cohort studies of children followed-up from birth born to HIV-1- infected mothers. We enrolled all uninfected children confirmed by HIV -1-DNA PCR, HIV-1 serology, or both. Late postnatal transmission was t aken to have occurred if a child later became infected. We calculated duration of follow-up for non-infected children from the time of negat ive diagnosis to the date of the last laboratory follow-up, or for inf ected children to the mid-point between the date of last negative and first positive results. We stratified the analysis for breastfeeding. Findings Less than 5% of the 2807 children in four studies from indust rialised countries (USA, Switzerland, France, and Europe) were breastf ed and no HIV-1 infection was diagnosed. By contrast, late postnatal t ransmission occurred in 49 (5%) of 902 children in four cohorts from d eveloping countries, in which breastfeeding was the norm (Rwanda [Buta re and Kigali], Ivory Coast, Kenya), with an overall estimated risk of 3.2 per 100 child-years of breastfeeding follow-up (95% CI 3.1-3.8), with similar estimates in individual studies (p=0.10). Exact informati on on timing of infection and duration of breastfeeding was available for 20 of the 49 children with late postnatal transmission. We took tr ansmission to have occurred midway between last negative and first pos itive HIV-1 tests. If breastfeeding had stopped at age 4 months transm ission would have occurred in no infants, and in three if it had stopp ed at 6 months. Interpretation Risk of late postnatal transmission is consistently shown to be substantial for breastfed children born to HI V-1-positive mothers. This risk should be balanced against the effect of early weaning on infant mortality and morbidity and maternal fertil ity.