PrEP could avert up to 8% of new infections by 2030

In 2015, the World Health Organization recommended pre‐exposure prophylaxis (PrEP) to all people at substantial risk of HIV. A key question facing countries is whether PrEP should be provided to adolescent girls and young women (ages 15 to 24), who experience high rates of infection, even though that rate is lower than other population groups, such as female sex workers and mixed-status couples.

To help answer this question, researchers modelled the impact and cost‐effectiveness of providing PrEP to different combinations of these three population groups in 13 countries between 2018 and 2030. The countries in question – Eswatini, Ethiopia, Haiti, Kenya, Lesotho, Malawi, Mozambique, Namibia, Nigeria, Tanzania, Uganda, Zambia and Zimbabwe – are home to 40% of the global population of people living with HIV but are all at different stages of PrEP delivery.

The first scenario imagined PrEP being nationally rolled out to female sex workers only; the second assessed national roll-out to female sex workers and mixed-status couples; the third assessed national roll-out for female sex workers and mixed-status couples, plus adolescent girls and young women in high prevalence areas. The final scenario imagined nationwide PrEP roll-out for all three populations.

For consistency, the modelling assumed access to antiretroviral treatment (ART) and voluntary medical male circumcision (VMCC) at 90%, in line with global targets. Cost‐effectiveness was calculated by comparing HIV programme costs (including cost savings associated with a reduced need for ART) for each HIV infection averted.

The modelling found PrEP could avert between 3% and 8% of HIV infections across the 13 countries by 2030. If PrEP was made available nationwide for all three population groups an estimated 230,000 HIV infections could be averted.

For all but Eswatini, Lesotho and Mozambique, only providing PrEP to female sex workers and mixed-status couples would prevent over half of the HIV infections likely to be averted by PrEP. In 8 of the 13 countries (Zambia, Zimbabwe, Malawi, Namibia, Nigeria, Tanzania, Haiti and Ethiopia), this scenario achieved more than 60% of the impact that rolling out PrEP nationally for all three groups would do.

Prioritising PrEP for adolescent girls and young women living in areas with high HIV prevalence was found to be more beneficial for countries with more concentrated or geographically focused epidemics, such as Nigeria, Tanzania, Haiti and Ethiopia. By comparison, in Lesotho, Eswatini and Mozambique, expanding PrEP to include adolescent girls and young women in all regions was likely to be more effective.

Researchers also modelled a scenario whereby VMMC and ART coverage was at 2017 levels. This found PrEP would become more cost effective and avert more HIV infections should ART and VMMC scale‐up stall.

Concerns that PrEP roll-out could have substantial impacts on the supply of antiretroviral drugs was not found to be true in any of the modelled scenarios.

Due to insufficient data, people who inject drugs and men who have sex with men were not included in the modelling exercise, which limits the study’s findings. In addition, the study’s authors emphasise that the cost‐effectiveness results should be “interpreted with extreme caution” as they were not derived from country‐specific costings.

Despite these limitations, this analysis suggests PrEP has the potential to substantially impact HIV epidemics, while highlighting the challenges facing countries as they consider the trade-off between preventing new HIV infections and cost.