Ontario is offering Oxford-AstraZeneca COVID-19 vaccines to residents aged 55 and older.
The number of pharmacies offering shots is expanding to include locations in every public health unit.
Ontario expects 583,400 shots of the vaccine to arrive today and the government says pharmacies could start offering doses as early as Saturday.
It says more primary care offices and community locations across all 34 public health units will also start administering the vaccine.
Oxford-AstraZeneca shots were initially offered at more than 300 pharmacy locations in Toronto, Windsor-Essex and Kingston, going to people aged 60 and older.
Some physicians' offices in six health units were also initially distributing the shots to patients in that age cohort.
Click here to see a list of Niagara pharmacies offering the vaccine.