Potential effectiveness of long-acting injectable pre-exposure prophylaxis for HIV prevention in men who have sex with men: a modelling study

Lancet HIV. 2018 Sep;5(9):e498-e505. doi: 10.1016/S2352-3018(18)30097-3. Epub 2018 Jun 13.


Background: Oral pre-exposure prophylaxis (PrEP) prevents HIV infection in men who have sex with men (MSM); however, adherence is an ongoing concern. Long-acting injectable PrEP is being tested in phase 3 trials and could address challenges associated with adherence. We examined the potential effectiveness of long-acting injectable PrEP compared with oral PrEP in MSM.

Methods: We used an agent-based model to simulate HIV transmission in a dynamic network of 11 245 MSM in Atlanta, GA, USA. We used raw data from studies in macaque models and pharmacokinetic data from safety trials to estimate the time-varying efficacy of long-acting injectable PrEP. The effect of long-acting injectable PrEP on the cumulative number of new HIV infections over 10 years (2015-24) was compared with no PrEP and daily oral PrEP across a range of coverage levels. Sensitivity analyses were done with varying maximum efficacy and drug half-life values.

Findings: In the absence of PrEP, the model predicted 2374 new HIV infections (95% simulation interval [SI] 2345-2412) between 2015 and 2024. The cumulative number of new HIV infections was reduced in all scenarios in which MSM received long-acting injectable PrEP compared with oral PrEP. At a coverage level of 35%, compared with no PrEP, long-acting injectable PrEP led to a 44% reduction in new HIV infections (1044 new infections averted [95% SI 1018-1077]) versus 33% (792 infections averted [763-821]) for oral PrEP. The relative benefit of long-acting injectable PrEP was sensitive to the assumed efficacy of injections received every 8 weeks, discontinuation rates, and terminal drug half-life.

Interpretation: Long-acting injectable PrEP has the potential to produce larger reductions in HIV transmission in MSM than oral PrEP. However, the real-world, population-level impact of this approach will depend on uptake of this prevention method and its effectiveness, as well as retention of patients in clinical care.

Funding: National Institute on Drug Abuse and National Institute of Mental Health.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Anti-HIV Agents / administration & dosage*
  • Anti-HIV Agents / pharmacokinetics
  • Chemoprevention / methods*
  • Delayed-Action Preparations / administration & dosage*
  • Delayed-Action Preparations / pharmacokinetics
  • Disease Models, Animal
  • Disease Transmission, Infectious / prevention & control*
  • HIV Infections / prevention & control*
  • Homosexuality, Male*
  • Humans
  • Injections
  • Macaca
  • Male
  • Middle Aged
  • Pre-Exposure Prophylaxis / methods*
  • United States
  • Young Adult


  • Anti-HIV Agents
  • Delayed-Action Preparations