Characteristics of US Counties with Low Pre-exposure Prophylaxis (PrEP) Use and Limited Access to PrEP Prescribing Clinics.

Pre-exposure prophylaxis (PrEP) is central to Ending the HIV Epidemic, yet uptake in the United States remains low and geographically uneven. Counties with persistently low PrEP use and limited local PrEP-prescribing infrastructure may represent "PrEP deserts," where geographic and structural barriers to HIV prevention converge. Prior studies have relied on travel-time measures or census tract-level analyses, limiting county-level insight. We conducted an ecological study of 2,257 US counties by linking AIDSVu PrEP-use estimates (2019-2023) with 5,856 PrEP-prescribing clinics identified through the CDC National Prevention Information Network. PrEP deserts were defined as counties with PrEP use in the lowest quartile in at least 3 of 5 years and no in-county PrEP-prescribing clinic in 2025. Mixed-effects logistic regression with a state-level random intercept was used to identify characteristics associated with PrEP desert status. Compared with metropolitan counties, micropolitan counties had higher odds of PrEP desert status (aOR: 2.90; 95% CI, 2.10-4.01), as did rural counties (aOR: 2.12; 95% CI, 1.50-3.01). Each 1-percentage-point increase in the proportion of uninsured residents was associated with 17% higher odds of PrEP desert status (aOR: 1.17; 95% CI, 1.04-1.32). Compared with counties in the South, counties in the Midwest had higher odds of PrEP desert status, whereas counties in the Northeast had lower odds. PrEP desert counties were concentrated in nonmetropolitan areas, in the Midwest and South, and in counties with higher uninsurance rates. Expanding pharmacy-based PrEP services and telePrEP, alongside strategies to reduce financial barriers, may improve access and reduce geographic disparities in HIV prevention.