Incidence and window period residual risk of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus in United States blood donations, 2017 to 2023: The transfusion-transmissible infections monitoring system.

Background: The Transfusion-Transmissible Infections Monitoring System assesses trends in ~60% of the US blood supply. Donors with high-risk behaviors, including injection drug use, men having sex with other men, or exchanging sex for money/drugs were deferred for 12 months (12M) from 2016 to 2020 and 3 months (3M) from 2020 to 2023. Here we evaluate HIV, HBV, and HCV incidence and window-period residual risk (WPRR) in two ~3-year periods of 12M (2017-2020) and 3M (2020-2023) to identify any differences.

Methods: First-time (FT), repeat (RPT), and overall weighted incidence/100,000 person-years (phtpy) for HIV, HBV, and HCV were estimated based on serology and nucleic acid test results. WPRR was calculated by multiplying respective incidence by agent-specific WP. Fisher's exact test evaluated incidence changes between the two periods (α = 0.05).

Results: Overall weighted incidence for HIV, HBV, and HCV was 2.22, 1.59, and 0.53 phtpy versus 1.03, 0.93, and 0.16 phtpy in 12M and 3M periods, respectively. Overall WPRR per 1,000,000 donations for HIV, HBV, and HCV was 0.45, 0.63, and 0.53 versus 0.23, 0.43, and 0.16 in 12M and 3M periods, respectively. All comparisons by agent and by period were significant (p < .01).

Conclusions: Despite reducing donor deferral periods for many infectious risk behaviors, HIV, HBV, and HCV overall incidence declined from the 12M to 3M periods. WPRR also declined from 12M to 3M, remaining under 1 per 2,000,000 donations in the 3M period. Thus, changes in policy did not adversely impact the safety of the blood supply with respect to the major infectious disease agents.