The Potential Impact of Long-Acting Cabotegravir for HIV Prevention in South Africa: A Mathematical Modeling Study

J Infect Dis. 2021 Oct 13;224(7):1179-1186. doi: 10.1093/infdis/jiaa296.


Background: Although effective, some oral pre-exposure prophylaxis (PrEP) users face barriers to adherence using daily pills, which could be reduced by long-acting formulations. Long-acting cabotegravir (CAB LA) is a potential new injectable formulation for human immunodeficiency virus (HIV) PrEP being tested in phase III trials.

Methods: We use a mathematical model of the HIV epidemic in South Africa to simulate CAB LA uptake by population groups with different levels of HIV risk. We compare the trajectory of the HIV epidemic until 2050 with and without CAB LA to estimate the impact of the intervention.

Results: Delivering CAB LA to 10% of the adult population could avert more than 15% of new infections from 2023 to 2050. The impact would be lower but more efficient if delivered to populations at higher HIV risk: 127 person-years of CAB LA use would be required to avert one HIV infection within 5 years if used by all adults and 47 person-years if used only by the highest risk women.

Conclusions: If efficacious, a CAB LA intervention could have a substantial impact on the course of the HIV epidemic in South Africa. Uptake by those at the highest risk of infection, particularly young women, could improve the efficiency of any intervention.

Keywords: HIV prevention; South Africa; heterosexual transmission; long-acting cabotegravir; mathematical models.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-HIV Agents / administration & dosage*
  • Anti-HIV Agents / therapeutic use
  • Diketopiperazines / therapeutic use*
  • Female
  • HIV Infections / drug therapy*
  • HIV Infections / epidemiology
  • HIV Infections / prevention & control*
  • Humans
  • Male
  • Middle Aged
  • Models, Theoretical
  • Pre-Exposure Prophylaxis*
  • Pyridones / therapeutic use*
  • South Africa / epidemiology


  • Anti-HIV Agents
  • Diketopiperazines
  • Pyridones
  • cabotegravir