ABS 043: Estimating the number individuals in the US who might benefit from Pre-Exposure Prophylaxis (PrEP) for HIV

Samuel Lederman ¹ ² , Mark Thrun ²

¹ School of Public Health, Providence, RI
² Gilead Sciences Inc., HIV Prevention US Medical Affairs, Foster City, CA

Van Wickle (2025) Volume 1, ABS 043

Introduction: Pre-exposure prophylaxis (PrEP) is over 99% effective in preventing HIV, yet uptake remains low in the United States, especially among marginalized populations. This is despite the Centers for Disease Control and Prevention (CDC) estimating in 2015 and 2018 that approximately 1.2 million individuals would likely benefit from PrEP. However, these estimates are outdated, failing to account for recent demographic shifts and emerging data that have reshaped the landscape of HIV risk. In recent years, LGBTQ+ identification has nearly doubled among US adults, and in 2021, the CDC updated their PrEP clinical guidelines, now recognizing sexually transmitted infection (STI) diagnosis within the past 12 months as a standalone indication for PrEP, regardless of an individual's sexual orientation. Additionally, improved estimates that no longer rely on self-reported data suggest that the population of people who inject drugs (PWID) in the US is much larger than previously reported, emphasizing the need for an updated understanding of PrEP eligibility. This study aimed to provide a more comprehensive estimate of the US population that could benefit from PrEP by integrating recent data, accounting for evolving risk factors, and addressing limitations in previous methodologies. By refining the criteria for high-risk behaviors and incorporating more precise population estimates, this analysis seeks to inform public health planning and resource allocation, ultimately supporting efforts to end the HIV epidemic in the United States.

Methods: To estimate the number of individuals in the United States who could benefit from PrEP, this analysis updated previous CDC methodologies by incorporating three mutually exclusive subpopulations at highest risk for HIV: men who have sex with men (MSM), people who inject drugs (PWID), and heterosexually active adults. Risk behaviors were selected based on the 2021 CDC PrEP guidelines, which included engaging in condomless sex with casual partners within the past 12 months for MSM, receiving a diagnosis of bacterial sexually transmitted infections (STIs) within the past 12 months for both MSM and heterosexually active adults, and receptive sharing of injection equipment within the past 12 months for PWID. Population size estimates were derived from the National HIV Behavioral Surveillance Special Reports and US Census data. Final estimates for each subgroup were aggregated to form a national range of potential PrEP beneficiaries.

Results: This analysis estimates that approximately 8.3 to 10.2 million individuals in the US could benefit from PrEP, a figure 8 to 10 times higher than the previous CDC estimate of 1.2 million. This range includes 1.7 million PWID, 5.52 million heterosexuals, and 1.04 to 2.95 million MSM, depending on the criteria used for risk assessment. These findings underscore the importance of updating estimates to reflect current risk behaviors and population sizes, providing critical insights for targeted PrEP outreach and resource allocation.

Discussion: These updated estimates reveal a significantly larger PrEP-eligible population than previously recognized, reflecting critical shifts in risk behaviors and population demographics. This highlights the need for more inclusive and precise public health strategies, especially for marginalized groups like MSM, PWID, and Black and Hispanic heterosexuals, who remain disproportionately impacted by the HIV epidemic. Future research should focus on refining these estimates to account for intersecting risk factors and geographic variations, ensuring that PrEP outreach effectively reaches those at greatest risk and supports broader HIV prevention goals in the United States.