The government claims that this is a relatively new problem, as until the end of last year the supply of doses was in line with demand. However, the use of vaccines has slowed despite the government and health authorities urging people to get a booster shot.
More than 80 percent of Canadians are fully vaccinated, and 57 percent of adults and 15 percent of teens have received their third dose of the vaccine.
However, coverage is significantly lower than before, from a peak of 600,000 doses per day in June to 250,000 in January and about 30,000 daily for the last month.
To date, less than two percent of Canada's stock of COVID-19 vaccines has expired.
University of British Columbia infectious disease expert Dr Srinivas Murthy says losing some doses due to expiration dates is normal in vaccine distribution campaigns.
Murthy said Canada should have done more sooner to make vaccination easier in low-income countries by supporting changes to licensing and manufacturing laws so vaccines can be made in more places.
There are currently 18 million doses of the vaccine available in Canada, and the vast majority of them will expire within the next four months.