Modelling the potential impact of providing preexposure prophylaxis in pregnant and breastfeeding women in South Africa

Objective HIV-uninfected pregnant and breastfeeding women are at high risk of HIV acquisition, contributing to vertical transmission of HIV. Preexposure prophylaxis (PrEP) is safe in pregnancy, but PrEP in pregnancy is not policy in many countries including South Africa. We evaluated the potential impact of providing PrEP for pregnant/breastfeeding women using a HIV model for South Africa. Methods Our model considers two scenarios: a conservative scenario that matches the experience reported in the Kenyan PrEP programme for pregnant women (probability of uptake = 32% and 11% in high-risk and low-risk women, respectively); and an optimistic scenario with PrEP initiated by 80% of all pregnant women. We compared this with PrEP for female sex workers, MSM and adolescent girls/young women. Women are assumed to remain on PrEP throughout pregnancy and breastfeeding, and an equivalent average PrEP duration (2 years) is assumed in other scenarios. Results Between 2020 and 2030, if PrEP is provided to pregnant/breastfeeding mothers, we project a 2.5% reduction in total HIV transmission [95% credibility interval (CI): 2.4-2.6%] in the conservative scenario and 7.2% (95% CI: 6.8-7.5%) in the optimistic scenario, which is similar to that in the female sex worker and MSM PrEP scenarios (1.9% and 3.0%, respectively). Without PrEP, 76 000 (95% CI: 64 000-90 000) new cases of vertical transmission are expected; PrEP provision may reduce these infections by 13% (95% CI: 13-14%) in the conservative scenario and 41% (95% CI: 39-44%) in the optimistic scenario. Conclusion High levels of uptake of and adherence to PrEP among pregnant/breastfeeding women could substantially reduce maternal and infant HIV acquisition in South Africa.