The agency responsible for most of Canada's blood supply says people who have travelled outside of Canada, the continental United States and Europe will be ineligible to give blood for 21 days after their return.
Canadian Blood Services says it is implementing the waiting period to mitigate the risk of the Zika virus entering the Canadian blood supply.
In a release Wednesday, Canadian Blood Services says the new waiting period is being implemented across the country and will take full effect in all of its clinics starting on Feb. 5.
Quebec's blood operator, Hema-Quebec, will be implementing the same change as of this Sunday.
Canadian Blood Services says the 21-day period ensures enough time has passed for the virus to be eliminated from a person's bloodstream, but it is asking people to postpone blood donation for at least a month after returning from travel outside the specified zones.
The three-week waiting period also applies to cord blood and stem cell donors who have travelled to affected areas. The waiting period begins the day a person returns to Canada.
Canadian Blood Services says the risk of a Canadian donor transmitting the Zika virus to a blood recipient is very low, adding that the mosquito that carries the virus does not live in Canada due to the colder climate.
There have been very few reported cases of Zika virus infection in Canadians who travelled abroad.
"This new temporary deferral period will safeguard Canada's blood supply against the Zika virus, and will also help us protect against other similar mosquito-borne viruses," Dr. Dana Devine, chief medical and scientific officer for Canadian Blood Services, said in a statement.
Canadian Blood Services said it anticipates the ineligibility period will reduce the number of donors available to donate in the coming months and is urging Canadians to donate before they travel to help make up for the anticipated shortfall.
Canadian Blood Services manages the national supply of blood, blood products and stem cells, and related services for all the provinces and territories – excluding Quebec.