Justice Horace Krever's emphasis on "preventive" action to ensure safe blood products is directly responsible for Health Canada's recent decision to ban blood donations from Canadians who spent a cumulative total of 6 months or more in the United Kingdom between 1980 and 1996. The ban was imposed to avoid donations from people infected with variant Creutzfeldt-Jakob disease.
In making the announcement Aug. 18, Dr. Doug Kennedy of Health Canada's Bureau of Biologics and Radiopharmaceuticals quoted from Krever's report: "Preventive action should be taken when there is evidence that a potential disease-carrying agent is or may be blood borne, even when there is no evidence that recipients have been affected." He also stated: "If there are no measures that will entirely prevent harm, measures that may only partially prevent transmission should be taken."
That is precisely the tactic pursued under the Health Canada ban, which Canadian Blood Services (CBS) put into effect Sept. 30 - 5 months before the government deadline. The new directive is a "compromise" between risk and benefit, said Kennedy. It is "strictly a precautionary measure" given that there is only a theoretical risk of contracting the fatal brain disorder through the blood supply. The US has introduced a similar ban.
The years between 1980 and 1996 were selected because that is thought to be the period when bovine spongiform encephalopathy (mad cow disease) evolved in the UK. The 6-months' cumulative time was based on data that indicated "we would get rid of 80% to 90% of the risk but only defer about 3% of donors across Canada," said Kennedy. "We want to avoid blood shortages," he added.
CBS estimates the deferred 3% of donors donate 20 000 units of blood annually. CBS has launched a publicity campaign to increase the number of donors and frequency of donations to make up for the anticipated shortfall.
"Our greatest concern is that people will stop donating without reason," said CBS chief executive officer Lynda Cranston. Donors are urged to contact their local CBS blood centre or call 888 760-8545 to determine if they are still eligible. CBS will also be monitoring hospitals to determine the policy's impact.
No cases of variant CJD have been reported in North America. There is no known treatment and no way to screen blood donors for it.