royng

I'm not educated in blood transfusion science at all...WHO guidelines (P.86) (at https://www.who.int/bloodsafety/publ...uitability/en/) quote that

To date, many countries have addressed this risk by excluding blood donors with a history of travel or residence in the UK and parts of Europe, for defined cumulative exposure periods. The United States Food and Drug Administration currently requires deferral of individuals who have spent 3 months or more cumulatively in the UK between 1980 and the end of 1996, when effective measures were implemented to prevent oral transmission, or who have spent 5 years or more cumulatively in Europe between 1980 and the present. In the UK, France and Ireland, recipients of blood transfusion (including fractionated blood products) since 1980 are now permanently deferred. Other countries defer donors who have received blood transfusions in the UK or France since 1980.

and WHO recommends that
The decision to defer blood donors with a history of travel or residence for defined cumulative exposure periods in specified countries or areas, as a measure to reduce the risk of transmitting vCJD by blood transfusion, should be based on the findings of the risk assessment and risk-benefit analysis and the impact on the blood supply