WINNIPEG -- The province of Manitoba is dropping the age eligibility for COVID-19 vaccines, and says it plans to continue expanding age eligibility regularly as supplies allow.

During a vaccine briefing on Wednesday, Johanu Botha, co-lead of Manitoba’s Vaccine Implementation Task Force, said people age 45 years or older can book a vaccine appointment beginning at 11:45 a.m. Wednesday.

Dr. Joss Reimer, the medical lead of the Vaccine Implementation Task Force, said this is the largest age jump in the province.

"This is one of the largest age-based expansions we have announced so far, which reflects more vaccine now being available to us," said Reimer.

Indigenous Manitobans age 18 years and older have been able to book a COVID-19 vaccine appointment since Monday.

Botha said the province has completed its community-based eligibility expansions, and will now focus on age eligibility.

"We have reached more than 40 per cent of adults immunized and more than half a million doses administered," said Botha.

He said age eligibility will continue to expand regularly going forward on Mondays, Wednesdays, and Fridays, as vaccine supplies and available appointments allow.

The province estimates all adults in Manitoba will be eligible for a vaccine by May 21. Botha confirmed all Manitoba children age 12 and up will also be eligible for a COVID-19 vaccine by May 21.

This comes hours after Health Canada approved the Pfizer vaccine for children 12 years and older.

"Our team is reviewing that information," said Reimer. "We want our clinical team to come up with recommendations, very shortly, so that we can share with all Manitobans exactly how we plan to do the rollout for those Manitobans. So we don't have the exact details to share today, but we do intend to include eligibility for younger Manitobans along with adults as we move forward."

READ MORE: Children 12 and older now cleared to receive Pfizer vaccine: Health Canada

Botha said second-dose appointments will begin once first-dose eligibility is complete, likely around May 22.

He said the first groups who will be eligible to book second doses will be people who are immunocompromised or have specific priority medical conditions.

"The second doses will begin going into arms no later than mid-June," Botha said.

He said after this group, the plan is to move down based on when people received their first dose.

"That timeline overall will be supply-dependent, but we will, of course, be able to move through our second dose campaign much faster than our first dose campaign because of the amount of supply coming into the province," Botha said.

He said the province anticipates the second dose campaign will be done by the end of July.

Vaccine appointments for a supersite can be booked by calling 1-844-626-8222 or by booking online.