Characterizing Viral Load Burden Among HIV-Infected Women Around the Time of Delivery: Findings From Four Tertiary Obstetric Units in Gauteng, South Africa

Background: Elimination of mother-to-child transmission of HIV requires sustained viral load suppression during pregnancy and breastfeeding among women living with HIV (WLHIV). Antenatal antiretroviral therapy coverage is reported at >95% in South Africa, but viral load suppression rates are unknown. We describe maternal VL burden around time of delivery at 4 tertiary obstetric units (TOUs) in Gauteng Province.

Methods: Between June 2018 and March 2019, routine point-of-care (PoC) maternal HIV VL and early infant diagnosis (EID) testing were implemented at 3 TOUs in Johannesburg and 1 in Tshwane district. WLHIV and HIV-exposed neonates were eligible for HIV VL (Xpert HIV-1 VL) and EID (Xpert HIV-1 EID or m-PIMA HIV1/2 detection) testing around time of delivery, respectively. Proportions of viremic women and intrauterine (IU)-infected neonates were calculated among valid PoC results.

Results: Among 8147 live births to WLHIV, 2769 (34.0%) women and 4333 (53.2%) neonates had valid PoC results. Median VL at delivery was <40 copies/mL (interquartile range: 0-398). The proportion of women with a VL < 50, 50 to <1000, and ≥1000 copies/mL was 63.6%, 13.9% and 22.4%, respectively. There were 65/4333 (1.5%) IU-infected neonates. Among 1449 mother-neonate pairs with both VL and EID results, IU transmission by VL threshold was 3/946 (0.3%), 6/187 (3.2%), and 25/316 (7.9%) for VL < 50, 50 to <1000, and ≥1000 copies/mL, respectively (P < 0.001).

Conclusions: Despite high antiretroviral therapy coverage, >1/3 of WLHIV had a VL ≥50 copies/mL at delivery. Among mother-neonate pairs, maternal VL ≥50 copies/mL accounted for 31/34 (91%) IU infections. Improvement in the quality of HIV care among WLHIV is essential if South Africa is to achieve elimination of mother-to-child transmission.