Getting people who have previously used HIV prevention medication to restart it may be more effective at reducing new infections than trying to recruit people who have never used it before. That is the central finding of a network modeling study published in Lancet Regional Health Americas, which examined HIV prevention strategies among men who have sex with men in Boston.
Researchers built a model of 100,000 cisgender men who have sex with men between the ages of 15 and 65, drawing on electronic health records from 37,722 patients collected between 2012 and 2023. The population in the model reflected Boston's demographics, with 21.5 percent identifying as Black, 18.9 percent as Hispanic, 44.5 percent as White, and 15.1 percent as other.
The study focused on pre-exposure prophylaxis, known as PrEP, a medication that dramatically reduces the risk of contracting HIV when taken consistently. A decade of PrEP availability has lowered HIV rates among gay and bisexual men, but not enough to meet federal Ending the HIV Epidemic goals. Racial and ethnic disparities in who uses PrEP and who contracts HIV have also persisted throughout the PrEP era.
The researchers compared three strategies: getting more people who have never used PrEP to start it, keeping current users on it longer, and getting former users to restart it. The reinitiation strategy outperformed the others by a significant margin. Doubling the rate at which former users restarted PrEP averted 15.8 percent of infections, compared to 10.0 percent for doubling new uptake and 5.6 percent for maximizing how long current users stayed on the drug. Scaling reinitiation to five times the baseline rate averted 32.6 percent of infections at the same number needed to treat.
The efficiency advantage comes from the fact that former PrEP users already know how the medication works, have an existing relationship with a prescribing provider, and face fewer logistical barriers to getting back on the drug than someone starting for the first time. Researchers described reinitiation as a prevention-side equivalent to re-engaging HIV-positive patients in antiretroviral therapy after they drop out of care.
The study also found that focusing reinitiation efforts specifically on Black and Hispanic men produced the most favorable patterns for reducing racial and ethnic disparities in HIV rates. Those disparities did not disappear under any of the modeled scenarios, but equity-focused reinitiation produced better outcomes on that measure than the other two strategies.
Researchers suggested that existing health infrastructure could support reinitiation efforts without requiring entirely new systems. Electronic health record alerts triggered when a former PrEP user returns for any kind of medical visit could prompt providers to discuss restarting the medication. That kind of prompt requires no new enrollment process and targets people who already have a foothold in the health care system.
The study was funded by the U.S. National Institutes of Health and the Emory Center for AIDS Research.
