Blood transfusion risk: protecting against the unknown

Worries over variant CJD should not detract from work on other, better known, risks

News p 726

In relation to viruses— which, classically, have posed the greatest potential risk to transfusion recipients—British blood is among the safest in the world. For HIV, the risk per unit of transfusion is about 1 in 2.5 million.1 But British blood services are now faced with the challenge of managing a potential risk from the transmissible spongiform encephalopathies, notably variant Creutzfeldt-Jakob disease. This challenge is particularly difficult given the lack of firm data on either the likely scale of variant Creutzfeldt-Jakob disease infection in Britain or the likelihood that the causative agent is present in and transmissible by donated blood. The announcement by the Department of Health, following advice from the Committee on Safety of Medicines, on 26 February of “further precautionary measures” in relation to the use of British plasma in blood products brings the challenge sharply into focus.

In March 1997 the World Health Organisation concluded that there is no proved or even probable instance of transmission of Creutzfeldt-Jakob disease by blood, blood components, or plasma derivatives, though it did identify a requirement to assess further the potential risk posed to transfusion by variant Creutzfeldt-Jakob disease.2 Lack of evidence of risk is not evidence of absence …