TORONTO — Canada’s largest province says it will stop giving out first doses of the Oxford-AstraZeneca vaccine due to concerns over blood clots.

Ontario Chief Medical Officer of Health Dr. David Williams says the decision has been made out of an abundance of caution because of increased instances of a rare blood clotting disorder linked to the shot.

AstraZeneca is restricted in some European countries because of a potential link to extremely rare blood clots. In Canada, at least 12 cases have been confirmed out of more than two million doses given and three women have died.

Ontario says it has 49,280 doses of the shot remaining in the province out of over 707,000 received. Health officials are awaiting results of a clinical trial in the United Kingdom looking at giving a different vaccine for the second dose. That would allow people who got AstraZeneca first to be given Pfizer or Moderna for their second dose.