1.5 million doses of the Oxford-AstraZeneca COVID-19 vaccine are scheduled to arrive Tuesday in Canada by truck from the United States – the first COVID vaccine doses to come from the U.S.

The shipment arrives as medical officers of health for all provinces and territories agree to suspend use of the vaccine for those under the age of 55, pending the results of further study.

The decision is based on guidance from the National Advisory Committee on Immunization over concerns about a possible link between the AstraZeneca vaccine and rare blood clots in mostly younger women in Europe.

“We’re looking at a rare risk of this potential adverse event (the severe clotting event with low platelet counts)compared to what your likelihood of having COVID, catching COVID and actually having an outcome that’s also very severe,” explained Health Canada’s Chief Medical Advisor Dr. Supriya Sharma.

Here in Ontario, the AstraZeneca COVID-19 vaccine has so far only been given to people 60 and over as part of the growing roll out in pharmacies and doctors’ offices.

For those who have had an AstraZeneca vaccine, Dr. Howard Njoo, Canada’s deputy chief medical officer of health, is offering advice.

“For those who have been vaccinated with AstraZeneca for fewer than 20 days and anyone vaccinated with the AstraZeneca vaccine going forward, you should seek immediate medical attention in the rare event that you develop symptoms starting four days or more after vaccination, such as shortness of breath, chest pain, leg swelling, persistent abdominal pain, sudden onset of severe or persistent worsening headaches or blurred vision or skin bruising, other than at the site of vaccination,” explained Dr. Njoo.

As for whether the AstraZeneca vaccine will be ultimately given to people aged 55 to 59 in Ontario, Chief Medical Officer Dr. David Williams says the province will await further guidance from the federal government.