Jones JM, et al. - Given that using nucleic acid tests (NAT), donors are universally screened for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) to reduce the risk of transmission of these infections through organ transplantation and that deceased organ donors are classified as “increased risk” if they engaged in specific behaviors during the 12 months before death, researchers sought to develop a model that could estimate the risk of undetected infection for HIV, HBV, and HCV among NAT-negative donors. They specifically considered the type and timing of donors’ potential risk behavior in order to guide revisions to the 12-month timeline. The estimated model parameters were risk of disease acquisition for increased risk groups, number of virions that multiply to establish infection, virus doubling time, and limit of detection by NAT. For HIV, the risk of undetected infection was <1/1 000 000 after 14 days, for HBV after 35 days, and for HCV after 7 days from the time of most recent potential exposure to the day of a negative NAT. Findings suggest the possibility for safe shortening in the period during which reported donor risk behaviors result in an “increased risk” designation.