Often confused with the similar-sounding “permanent deferral,” an indefinite deferral is applied to a blood donor who cannot “donate blood for someone else for an unspecified period of time.” While this sounds like a permanent deferral (and it functionally is a permanent deferral), an indefinite deferral leaves a slight “crack in the door” for the donor to regain eligibility at some point in the future if rules change or testing improves, etc. The vast majority of the testing and historical results that lead a donor to be ineligible long-term are actually indefinite deferrals and not permanent ones. The long list includes laboratory testing indicative of HIV, hepatitis B, or hepatitis C infection, a history of IV drug use, dura mater transplants, and travel and family history indicating a risk of infection with variant Creutzfeldt-Jakob disease (vCJD).