Achieving and maintaining viral suppression (VS) in people living with HIV/AIDS on antiretroviral therapy (ART) remains a crucial clinical goal, more so in pregnancy to prevent mother-to-child-transmission (MTCT). There is a need to understand VS kinetics and barriers to achieving it in order to meet the target of eliminating HIV-MTCT by 2030.
HIV-infected pregnant women ≥20 weeks of gestation with different durations of Tenofovir/Lamivudine/Efavirenz exposures seeking antenatal care services at four primary health centres in high-density residential areas in Harare, Zimbabwe were enrolled in the University of Zimbabwe Birth Cohort Study. Plasma viral load (VL) was quantified by reverse transcriptase–polymerase chain reaction. Demographic, clinical, socio-economic and HIV- and ART-related factors were tested in multivariable logistic regression analyses as potential predictors for VS and undetectable VL.
From March 2016 to June 2019, 608 HIV-infected pregnant women were enrolled. 63 (10.4%) were self-reported-ART-naïve; 324 (53.3%) and 221 (36.3%) initiated ART pre- and post-conception, respectively. Time from ART initiation to VS (VL ≤ 1,000 copies/ml) in 95% of the women was 126 days. Overall lack of VS (VL > 1,000 copies/ml) was observed in 133 (21.9%) women being 76.2, 27.4 and 7.7% in self-reported-ART-naïve, post-conception and pre-conception groups, respectively. Undetectable VL (≤ 50 copies/ml) was observed in 371 (61.2%) and low-level viremia (51–1,000 copies/ml) in 102 (16.8%) women.
In multivariable models for all participants regardless of ART exposure, being on ART was the strongest predictor for both VS and undetectable VL (odds ratio 95% confidence interval, OR (CI): 8.9(4.2–19.5) and 8.1(3.2–24.4), respectively). For women on ART, duration of ART use >126 days was the strongest predictor with OR (CI): 6.7(3.3–14.0) for VS and 8.5(5.6–13.1) for undetectable VL. Other relevant predictors for favourable virological outcomes were older maternal age, HIV-status disclosure, absence of ART side effects and self-reported depression. Having a spouse/intimate partner on ART predicted a 4 times higher likelihood for VS.
Lack of VS was frequently observed in this Harare cohort of pregnant women, mainly due to new HIV diagnosis, hence not being on ART and suboptimal duration of ART exposure. Since VS for 95% of women needed about 4 months of ART exposure, eliminating HIV-MTCT will require timely screening and commencing women together with their spouses/intimate partners on ART before pregnancy or early after conception.