Postnatal mother-to-child transmission of HIV and HIV-free survival in an HIV-exposed national cohort, South Africa, December 2012-September 2014

Background: Global targets for eliminating mother-to-child transmission of HIV (MTCT) are <2% by six weeks and <5% by 18 months postpartum. We measured population-level MTCT and infant HIV-free survival (HFS) from 4-8 weeks to 18 months (when Option A was policy) in South Africa.

Method:  A nationally representative cross-sectional survey was conducted in 580 public health facilities randomly selected using multistage probability proportional to size. We interviewed caregivers of infants aged 4-8 weeks receiving their six week immunisation and tested infant dried blood spots for HIV exposure (antibody) and infection. A closed cohort of HIV-exposed infants were invited for follow-up. At each visit we interviewed primary caregivers and tested infants for HIV infection.

Results: At 4-8 weeks, data from 9120 infants were analysed, showing 33.1% (95% Confidence Interval (CI) 31.8-34.3%) infant HIV-exposure and 2.6% (CI 2.0-3.2%) early MTCT. Of 2787 infants in the cohort, 1069 (38.3%) were lost to follow-up (LTFU) by 18 months. Cumulative (from birth) preliminary unweighted MTCT  by 3, 6, 9, 12, 15, and 18 months was 2.65%, 3.41%, 3.73%, 3.93%, 4.08% and 4.19%, respectively; preliminary HFS was 97.3%, 95.6%, 94.4%, 93.7%  93.2% and 92.9%..

Conclusions: Although preliminary unweighted 18-month MTCT was <5%, there is potential that global targets were not achieved as our data excludes early infections/deaths prior to 6 weeks postpartum and outcomes amongst LTFU infants. Our findings highlight the need for continued improvements in antenatal and perinatal PMTCT programmes and intense postnatal follow-up to remove bottlenecks and reach global targets.