"Right now, more contagious and risky variants are spreading and threatening the progress we've made", he said.
Australia's medicine regulator has identified a second case of rare blood clots believed to be linked to the AstraZeneca Covid-19 vaccine.
She had two conditions simultaneously, the ministry reported: thrombocytopenia with thrombosis. British authorities say the risk of such blood clots is 1-in-250,000 in that country.
"They may be due to one of the components of the vaccine or to the injection technique; they can also have other causes, which sometimes remain unknown".
People who have received the AstraZeneca vaccine have been asked to look out for symptoms including severe or persistent headaches, blurred vision, shortness of breath, chest pain, leg swelling or abdominal pain.
The woman received the vaccine produced at the Serum Institute of India, known as Covishield.
Authorities did not provide the woman's age, nor did they specify whether she is older than or younger than 55, which is the cut-off age now recommended by Canada's National Advisory Committee on Immunization.
A health worker prepares a syringe of the AstraZeneca Covid-19 vaccine in Munich, Germany.
Treasurer Josh Frydenberg said the setbacks in the vaccine rollout should not "derail momentum in our economic recovery".
The National Advisory Committee on Immunization and the Chief Medical Officers of Health continue to recommend pausing the use of the vaccine in adults under the age of 55 pending the results of the review.
"Obviously, we're following closely developments in the United States and we can assure everyone that Health Canada will every step of the way put the health of Canadians first and foremost in any decision we make around distributing vaccines", Trudeau said.
The risk of getting blood clots from COVID-19 itself is far higher than from the vaccine. Both products are under review by Europe's drug regulator after it found possible links with blood clots, although it has said the advantages still outweighed the risks.
Tam says an average of 970 people have been in ICUs over the last week.
At a press conference on Tuesday, Prime Minister Justin Trudeau indicated that doses of this vaccine are expect to arrive at the end of April.