TORONTO -- Ontario says the Oxford-AstraZeneca vaccine will be offered to individuals 40 years old and over in pharmacies and primary care settings starting on Tuesday.

A spokesperson for Health Minister Christine Elliott confirmed the change on Sunday evening.

There have been growing calls for the provincial government to make the vaccine more widely available as Ontario continues to see record numbers in COVID-19 cases and hospitalizations amid a third wave that is mainly driven by variants of concern.

"I can confirm that based on current supply, Ontario will begin offering the AstraZeneca COVID-19 vaccine to individuals aged 40 and over at pharmacy and primary care settings across the province effective Tuesday," the spokesperson said.

The AstraZeneca vaccine is currently available only to adults aged 55 and older following the recommendation from the National Advisory Committee on Immunization (NACI).

It is in response to cases of younger people developing rare blood clots after receiving the shot. On Saturday, Alberta reported that a patient who got the AstraZeneca vaccine developed a condition called a vaccine-induced immune thrombotic thrombocytopenia. It is the second case of the rare blood clot disorder in Canada.

Despite the two cases, Health Canada maintained that the benefits of the AstraZeneca vaccine outweigh the risks of getting COVID-19. The agency approved the use of the vaccine for those 18 years old and over.

Before the change was announced, federal Health Minister Patty Hajdu was asked during a news conference Sunday afternoon if she will support lowering the age for the AstraZeneca vaccine in Ontario.

"Provinces and territories are free to use AstraZeneca in any age population over 18 as per Health Canada’s license for use in Canada," Hajdu said.

"NACI provides recommendations based on the current evidence and evolves their advice as new evidence comes in. In fact, they are reviewing AstraZeneca advice now, and we'll have an update in the near future. But there was nothing stopping the province of Ontario for changing their advice for use to their physicians within Ontario."

She said 4.8 million doses of vaccines have been delivered to Ontario to date, with 3.8 million shots administered. Hajdu added that 395,000 doses are coming this week.

Dr. Isaac Bogoch, who sits on the province’s COVID-19 Vaccine Distribution Task Force, told CP24 last week that the AstraZeneca vaccine, which is available in more than 1,400 pharmacies,  is “not flying off shelves.”

According to the province, it received 538,400 doses of the vaccine between March 29 and April 4 as part of a U.S. loan deal with Canada. A spokesperson for the government said last Thursday that 500,000 of those doses have been delivered to pharmacies and doctors’ offices but have yet to be administered.

In an effort to dispel concerns over the vaccine, Premier Doug Ford, Minister Elliott and Toronto Mayor John Tory all received their first dose of the AstraZeneca shots on camera.

The vaccine rollout in the province has also been hampered by the delays in shipment of the Moderna doses, resulting in several immunization clinics closing and appointments being cancelled.

On Sunday morning, a spokesperson for the provincial government said Premier Doug Ford has begun reaching out to international allies to secure more supply.

The government reiterated that Ontario has the capacity to ramp up vaccinations, but it has been challenging due to the lack of supply.

“Vaccines are our only way out of this pandemic, and the Premier will exhaust every avenue he has in order to get more needles into the arms of Ontarians sooner,” the province said. Many public health experts had said that the province will not be able to vaccinate its way out of the third wave.

Several Ontario physicians took to social media Sunday to welcome the announcement of the new minimum age for the AstraZeneca vaccine.

Dr. Michael Warner, the head of critical care at Michael Garron, called the change a “great move” and urged the province to divert all supply to pharmacies in hot spot areas. He also said the government should contact employers to cover vaccination time off for essential workers.

Dr. Steve Flindall, an emergency doctor in York Region, said in a tweet that “this is the best news I’ve seen all weekend.”

“I literally broke down in tears with the thought that my wife could start getting vaccinated this week,” Flindall tweeted.

Brampton Mayor Patrick Brown said he will sign up for the AstraZeneca vaccine and urge those eligible to book their appointments.

Meanwhile, Ontario Liberal Leader Steven Del Duca called it a good start but said the AstraZeneca vaccine should be available to anyone 18 and older.

“Doug Ford must release the AstraZeneca vaccine from pharmacy freezers and get it into the arms of anyone over 18 in a hotspot. Minister Hajdu was clear: there is nothing stopping him from getting shots into arms,” he said in a news release.

On Sunday, Ontario reported 4,250 new COVID-19 cases and 18 more deaths. The number of COVID-19 patients in ICUs increased from 726 to 741.

- with files from Joshua Freeman and The Canadian Press