Ontario plans to follow federal recommendations to only administer the AstraZeneca COVID-19 vaccine to people under the age of 65, the province’s health minister confirms, but it remains unclear who will receive those shots when they arrive in the country this week.

Under the current phase of the province’s vaccination program, only members of the general population who are over the age of 80 are being prioritized for a COVID-19 vaccine and the province says it will still have to figure out who to administer AstraZeneca shots to when the new shipments arrive.

“Right now, we're doing the calculation based on the AstraZeneca vaccine coming into the mix,” Ontario Health Minister Christine Elliott told reporters at Queen’s Park on Tuesday.

“This is something that we did after we got started with Pfizer and then we introduced Moderna. In the same way, we're building AstraZeneca into the plan as well.”

The AstraZeneca vaccine was approved by Health Canada just last week and Ontario is expecting to receive more than 100,000 of the 300,000 doses that have now been shipped to Canada. Those doses are set to arrive in the country on Wednesday and will expire on April 2.

While some regions of the province have begun to roll out vaccines to a small number of seniors who live in the community, many municipalities, including Toronto, are waiting for the launch of Ontario’s vaccination booking system before beginning to inoculate members of the general population. The province’s online appointment portal does not officially go live until March 15.

When asked why the vaccine booking system wasn’t available sooner, the province said it wanted to run further tests to ensure that it didn’t “crash,” as was the case in some other provinces following the launch of their online portals.

Members of the official opposition have accused the Ford government of being “unprepared” for the influx of vaccines.

“We're literally days away from AstraZeneca arriving, why isn't the government being upfront, being clear, being transparent about what the plan is,” Ontario NDP Leader Andrea Horwath said Tuesday.

The AstraZeneca vaccines aren’t the only thing that has forced the province to retool their vaccination strategy, Elliott said.

The province is also waiting for federal guidance on whether second doses should be delayed.

On Monday, British Columbia confirmed that it plans to extend the time between the first and second doses of the Pfizer and Moderna vaccines to four months and Ontario’s health minister and solicitor general have confirmed that the Ford government is now looking into the possibility of pushing back second doses as well.

This would mean many more people in the province could receive their first dose sooner than initially expected.

“This could make a significant difference for Ontario in reducing hospitalizations and deaths,” Elliott said Tuesday.

“As soon as we receive that [recommendation] we will be able to finalize the plan and get in front of you.”

Many essential workers in the province are also waiting for clarity on when they will receive a COVID-19 vaccine.

Last week, Retired Gen. Rick Hillier, chair of Ontario’s vaccine distribution task force, said the province hopes to begin vaccinating essential workers in May but provided no further details about who would be included in that group.

-With files from CTV Toronto’s Colin D'Mello