Canadian health authorities announced Saturday they were pushing back the expiration date on nearly 50,000 doses of AstraZeneca coronavirus vaccine by one month.

Health Canada said in a statement its approval to extend the shelf life of two lots of vaccine from May 31 to July 1 was supported by "scientific evidence."

"This change will ensure that provinces and territories are able to use up their existing inventory and provide Canadians access to much needed doses of the vaccine," the agency said.

A spokesperson for Health Canada said that as of May 22, there were about 49,000 doses of AstraZeneca in the country with an expiration date of May 31. CBC reported that most were in Ontario province.

Canadian health authorities had previously approved a six-month shelf life for AstraZeneca's Covid-19 vaccine.

People receive their Covid-19 shot during a "Doses After Dark" overnight vaccination clinic in Mississauga, Ontario on May 15, 2021
People receive their Covid-19 shot during a "Doses After Dark" overnight vaccination clinic in Mississauga, Ontario on May 15, 2021 AFP / Cole BURSTON

But they said they received information from the company on May 27 including "product stability and mathematical modelling data" that showed the two lots could be safely and effectively used for an extra month.

Several provinces announced this month their decision to suspend use of the AstraZeneca vaccine for people receiving their first shot, due to rare instances of blood clots.

But Canadians who had received a first AstraZeneca dose were able to get their scheduled second dose.

Just over 55 percent of Canada's 38 million people have received one dose of Covid-19 vaccine, and 5 percent have received two doses.

In addition to AstraZeneca, vaccines from Pfizer, Moderna and Johnson & Johnson are approved for use in Canada.

Coronavirus