Do young women base their PrEP use on their HIV risk?

New research suggests some adolescent girls and young women are using PrEP correctly, after a clear link was found between PrEP adherence and risky behaviour. But many are still underestimating their HIV risk or are unable to act on it.

What is the research about?

The link between HIV risk and PrEP use among adolescent girls and young women in South Africa and Zimbabwe.

Researchers analysed data from a PrEP trial involving 427 sexually active young women (ages 16–25). Each young woman took part in the trial for a year. Half got standard PrEP adherence support (based on self-reported adherence). The other half got standard support, plus counselling based on test results showing the level of PrEP in their blood.

Researchers assessed the link between risky behaviour (such as having sex without a condom or exchanging sex for money or gifts) during the past three months and PrEP adherence.

Why is this research important?

Adolescent girls and young women in East and Southern Africa are three times more likely to get HIV as males their age. PrEP prevents HIV infection when it is taken consistently, so ensuring adolescent girls and young women can access it is important.

But PrEP is only meant to be taken during periods of high HIV risk, and this will be different for different young women. To use PrEP effectively, young women need to be able to assess their personal HIV risk and respond to it correctly. Yet adherence studies tend to base ‘success’ on things like pills counts instead of linking adherence with HIV risk.

What did they find out?

Young women were significantly more likely to take PrEP consistently when they were involved in at least one behaviour that increased their risk of HIV. As young women’s HIV risk fell, so did their PrEP adherence. This link was found among the group that had enhanced counselling alongside standard support.

When the study began, 85% of participants reported at least one HIV risk behaviour. This fell to 60% at three months (week 13), and it stayed around this level for the rest of the study (61% at week 52). The biggest decline in risky behaviour related to having sex without a condom.

During the study, 1% of young women got HIV. This is almost four times lower than the infection rate for young women in both countries. This suggests some young women were judging their HIV risk accurately enough to use PrEP effectively.

It is important to note that only one in five young women engaged in risky behaviours consistently took PrEP. This suggests most young women engaged in risky behaviours either underestimated their personal risk or did not adhere to PrEP for other reasons.

Around half of all participants reported depression, intimate partner violence or post-traumatic stress. All of these things can make it hard for young women to take PrEP regularly.

What does this mean for HIV services?

PrEP programmes should not aim to ensure all young women consistently take PrEP. Rather, they should help young women identify if they are at risk of HIV then support them to take PrEP for as long as that risk exists. Programmes should also provide young women with enhanced counselling based on PrEP drug levels and accurate advice on how to safely stop and restart PrEP.

Asking supportive, open-ended questions about recent behaviours, experiences and relationships can help young women assess their HIV risk. Employing trained peer educators or friendly adults can help to build relationships of trust between PrEP providers and young women. This can help young women open up about the risks they face. It can also help them address other issues, such as depression or abuse, which might stop them from taking PrEP, even when they need it.