The Ontario government announced on Tuesday that it will be pausing the administration of first doses of the AstraZeneca vaccine.

Dr. David Williams, Ontario's chief medical officer of health, stated that the move is being made due to an increase of a rare blood clotting condition known as "vaccine-induced immune thrombotic thrombocytopenia (VITT)" that is linked to the vaccine.

"Effective today, Ontario will be pausing the rollout and administration of the first or initial doses of AstraZeneca vaccine at this time," Williams stated. "This decision was made out of an abundance of caution due to an observed increase in the rare blood clotting condition."

Public Health Ontario, the Science Advisory Table and federal, provincial and territorial partners will continue to review data to see if the AstraZeneca vaccine should be used as a second dose moving forward.

Dr. Jessica Hopkins, chief health protection and emergency preparedness officer at Public Health Ontario, stated that the risk of blood clotting linked to the AstraZeneca vaccine has increased from a risk of about one in 125,000 to a risk of one in 60,000 in Ontario.

However, Williams maintains that if you already got an AstraZeneca vaccine dose, you have done the right thing. "Based on the much higher risks of COVID-19 infection recently observed in Ontario, including hospitalization, serious illness and death, we maintain that those who received their first dose with the AstraZeneca vaccine did absolutely the right thing to prevent illness, and to protect their families, loved ones and communities."