Canadian Blood Services is calling on donors to book and keep appointments as it faces a decrease in collections.
The organization said Monday it currently has only four days worth of O+ blood type supply and five days worth of O- and B- blood types, along with six days worth of A- blood type and seven days worth of A+ and B+ blood types.
Spokeswoman Delphine Denis said collections have been steadily decreasing since July 1.
Denis said the blood-collecting agency closely monitors the days of the available blood supply.
"While three or four days on hand is challenging, we can turn this around with the help of new and returning donors," she said in a statement.
"Thanks to the support of donors across the country, we are one of few blood operators around the world that has not experienced a blood crisis or issued a national appeal during the pandemic."
She said ongoing illness and isolation requirements related to COVID-19, heat-related weather issues and the return of pre-pandemic activities and summer travel that have left many people with less time to donate are all factors contributing to the situation.
"Summer is always a challenging time for collections," she said, adding this is the first summer since 2019 where there are few restrictions on travel and other leisure activities.
The organization said the number of people who donate blood regularly decreased by 31,000 donors during the pandemic, leaving it with the smallest donor base in a decade.
It says there are 57,000 open appointments that must be filled before the end of August across Canada.
Denis said donors from all blood groups are urged to book appointments to donate blood right away or over the next few weeks leading up to Labour Day weekend.
She said the need for blood, plasma and platelets is constant, as people such as cancer patients, accident victims and those undergoing surgery rely on transfusions every day.
This report by The Canadian Press was first published Aug. 8, 2022.