New research on the proportion of adolescents and young adults (AYA) who are adherent to pre-exposure prophylaxis (PrEP) revealed that young cisgender women have a lower adherence rate than young men who have sex with men (MSM) and serodiscordant heterosexual couples.1

“The study that we conducted was a meta-analysis that was looking at, essentially, adolescents and young adults’ experience with pre-exposure prophylaxis,” says Bianca A. Allison, MD, MPH, assistant professor in the department of pediatrics at the University of North Carolina at Chapel Hill. “We were trying to determine across studies that have been done to investigate PrEP use in AYA what the adherence was overall. We looked at factors associated with PrEP adherence.”

Allison and colleagues compared adherence among groups divided by gender and risk categories. They looked at self-reported measures or biological measures like blood samples.

“We looked at the type of pill-taking regimen people were on and the different interventional components that might be related to PrEP adherence,” she explains. “We found that the majority of AYA did meet study-defined thresholds for adherence to PrEP.”

For instance, one of the thresholds for adherence could be someone who takes their pills four to seven days a week, Allison explains. Knowing the thresholds and what percentage of the population was adherent is helpful in understanding their adherence to other medications as well.

“The study’s findings were similar to findings that were shown in adherence to PrEP in older adults as well as other drugs like antivirals for HIV,” Allison says. “It is important that AYA are as adherent to this preventive medication as they might be for treatment for other conditions.”

For example, research on AYA and their adherence to oral contraceptives showed a similar range of adherence as they had to PrEP. “The studies that we included had a wide variety of populations that were studied,” Allison says. “There were several focused on cisgender women only, several on men who have sex with men or transwomen, and serodiscordant couples, especially outside of the U.S.”

The study’s broad findings were that 64% of young people were adherent to PrEP. “Some of the other findings were that self-reported methods of adherence, like asking someone how many times in the past month they had skipped a dose, were actually very reliable, and were similar to drug levels in their bloodstream,” Allison says. “We also found that cisgender women had the lowest adherence compared to MSM, transwomen, or serodiscordant couples.”

These findings suggest that clinicians need better intervention to increase PrEP adherence and acceptance among all populations — not just those deemed at the highest risk, she says.

Reproductive health providers could improve counseling and education for cisgender women who are at risk of HIV infection to increase their acceptance of PrEP.

“Our study found that a few aspects of intervention actually did not increase PrEP adherence, even though we thought they should,” Allison notes.

For instance, providing free PrEP or in-person counseling visits did not increase adherence. “One could hypothesize that these actions would increase access, but they didn’t,” Allison notes. “It is important for providers and clinicians to do some background research on their communities that require PrEP to better understand how to increase adherence in these populations. Because we covered a wide variety of populations, our final message is to learn your population and their needs to better help them be adherent to PrEP.”

Allison and colleagues concluded that researchers should study various interventions systemically to help increase PrEP adherence.

Another important finding was improved adherence to PrEP with daily dosing regimens. When people use PrEP on demand or because of a certain event, such as taking a dose right after sex, they showed much lower adherence than people who took a daily dose of PrEP.

“What we need to consider for the future is other ways to administer PrEP to increase adherence,” Allison says. “We need to look out for FDA-approved long-acting PrEPs like an implant or a vaginal ring that might actually improve adherence in the future.”

Reproductive health providers should learn the latest PrEP technology and look for new tactics that will help AYA improve access and adherence to PrEP, she explains.


  1. Allison BA, Widman L, Stewart JL, et al. Adherence to pre-exposure prophylaxis in adolescents and young adults: A systematic review and meta-analysis. J Adolesc Health 2021;S1054-139X(21)00169-5.