The potential benefits of long-acting injectable cabotegravir in pregnant and breastfeeding women and their infants: a modelling study

Abstract

Background: Pregnant and breastfeeding women (PBW) in sub-Saharan Africa have high HIV incidence rates and associated risk of vertical transmission to their infants. Oral pre-exposure prophylaxis (PrEP) and injectable PrEP (long-acting cabotegravir, or CAB-LA) can potentially reduce this HIV transmission, but population-level impacts are uncertain. Methods: We extended a previously-developed model of HIV and PrEP in South Africa to allow for variable PrEP duration and preference in PBW. We considered three potential scenarios for PrEP provision to PBW: oral PrEP only, CAB-LA only and allowing oral/CAB-LA choice, with uptake and retention assumptions informed by South African data, each compared to a ‘base’ scenario without PrEP for PBW. Results: Without PrEP for PBW, the model estimates 1.31 million new infections will occur between 2025 and 2035 in South African adults and children, including 100,000 in PBW, 16,800 in infants at/before birth, and 35,200 in children through breastmilk. In the oral PrEP only scenario, these numbers would reduce by 1.2% (95% CI: 0.7–1.7%), 8.6% (4.8–12.9%), 4.0% (2.1–5.8%) and 5.3% (3.0–8.2%) respectively. In the CAB-LA only scenario, the corresponding reductions would be 6.1% (2.9–9.6%), 41.2% (19.8–65.0%), 12.6% (6.0–19.4%) and 29.5% (13.9–46.8%) respectively, and in the oral/CAB-LA choice scenario, similar reductions would be achieved (5.6% [3.4–8.0%], 39.0% [23.4–55.9%], 12.4% [7.4–16.8%] and 27.6% [16.5–39.9%] respectively). Conclusion: CAB-LA has the potential to be substantially more effective than oral PrEP in preventing HIV acquisition in PBW and vertical transmission, and can also modestly reduce HIV incidence at a population level.