Impact of breastfeeding, maternal antiretroviral treatment and health service factors on 18-month vertical transmission of HIV and HIV-free survival: results from a nationally representative HIV-exposed infant cohort, South Africa

Background We analysed the impact of breastfeeding, antiretroviral drugs and health service factors on cumulative (6 weeks to 18 months) vertical transmission of HIV (MTCT) and 'MTCT-or-death', in South Africa, and compared estimates with global impact criteria to validate MTCT elimination: (1) <5% final MTCT and (2) case rate <= 50 (new paediatric HIV infections/100 000 live births). Methods 9120 infants aged 6 weeks were enrolled in a nationally representative survey. Of 2811 HIV-exposed uninfected infants (HEU), 2644 enrolled into follow-up (at 3, 6, 9, 12, 15 and 18 months). Using Kaplan-Meier analysis and weighted survey domain-based Cox proportional hazards models, we estimated cumulative risk of MTCT and 'MTCT or death' and risk factors for time-to-event outcomes, adjusting for study design and loss-to-follow-up. Results Cumulative (final) MTCT was 4.3% (95% CI 3.7% to 5.0%); case rate was 1290. Postnatal MTCT (>6 weeks to 18 months) was 1.7% (95% CI 1.2% to 2.4%). Cumulative 'MTCT-or-death' was 6.3% (95% CI 5.5% to 7.3%); 81% and 62% of cumulative MTCT and 'MTCT-or-death', respectively, occurred by 6 months. Postnatal MTCT increased with unknown maternal CD4-cell-count (adjusted HR (aHR 2.66 (1.5-5.6)), undocumented maternal HIV status (aHR 2.21 (1.0-4.7)) and exclusive (aHR 2.3 (1.0-5.2)) or mixed (aHR 3.7 (1.2-11.4)) breastfeeding. Cumulative 'MTCT-or death' increased in households with 'no refrigerator' (aHR 1.7 (1.1-2.9)) and decreased if infants used nevirapine at 6 weeks (aHR 0.4 (0.2-0.9)). Conclusions While the <5% final MTCT target was met, the case rate was 25-times above target. Systems are needed in the first 6 months post-delivery to optimise HEU health and fast-track ART initiation in newly diagnosed mothers.