TORONTO -- Ontario hit a new single-day vaccination record Tuesday as those 40 and over rushed to get shots of the AstraZeneca vaccine made available to them through a lowered age threshold at pharmacies.

Speaking with CP24 Wednesday morning, Dr. Isaac Bogoch said the vaccine is "flying off the shelves" at pharmacies, catapulting Ontario's vaccination numbers.

Ontario managed to give out 136,695 vaccine jabs by 8 p.m. Tuesday — roughly 46,000 doses more than the previous day and a new single-day record in the province’s vaccination effort.

The leap ahead comes after several days of lacklustre performance on the vaccine front with the province not having reached above 100,000 daily doses since Friday.

Bogoch sits on Ontario’s COVID-19 Vaccine Distribution Task Force. In a tweet, he credited the expanded eligibility for the boost in vaccinations, calling it “a big #COVID19vaccine day in Ontario.”

“This rise from ~100k/day is almost exclusively due to more AstraZeneca being administered,” he wrote.

The province did say Tuesday that some clinics had difficulty reporting vaccination numbers the day before because of the Rogers outage, but it is not immediately clear whether the numbers reported for Tuesday reflect some doses that were in fact administered on Monday.

Tuesday marked the first day that those 40 and over could book a vaccine shot at a pharmacy after the province lowered the age threshold for AstraZeneca.

While the vaccine has been approved for use in those 18 and older in Canada for several months, Ontario had abided by a recommendation from the National Advisory Committee on Immunizations (NACI) to only administer the vaccine to those 55 and over as it evaluated evidence linking the shot to rare blood clots.

With most people over 60 able to book a shot at clinics using other vaccines across Ontario, the policy meant that there was a very limited market for the AstraZeneca shot in the province. The premier’s office told CP24 last week that half a million doses of the vaccine remained unused from a shipment of roughly 586,000 received at the start of the month.

Ontario and several other provinces dropped the age threshold for AstraZeneca this week following calls to allow people to make the decision about whether to get it through informed consent.

Bogoch said that while there remains a risk factor for certain individuals, allowing a wider range of people to get the shot makes sense given the data showing that it is safe for most groups.

“I still think we have to at least be mindful that these blood clotting effects are not a zero per cent risk,”Bogoch said. “Some people say, lower the age range to 18 and let people have informed consent to take this vaccine if they want. Other people say you know what, when you're doing that risk-benefit calculation, there's probably an age cutoff and a sweet spot that's around the 30 to 40 year mark.”

He added that Ontario’s new 40 and over cutoff is “very reasonable for the time being.”

NACI was expected to provide updated guidance on use of the shot Tuesday, but abruptly cancelled a scheduled news conference.

Ontario poised to see influx of vaccines

More than four million doses of the AstraZeneca vaccine are expected to arrive in Canada from various sources between now and June, though a delivery schedule to the provinces has not yet been published by the federal government.

Provincial officials have said that some shipments that were expected to arrive this week and in mid-May have been delayed and it is not yet clear when the province will receive a new influx of the vaccine.

However Ontario is set to see nearly a doubling of its weekly deliveries of Pfizer starting the first week in May. While the province is currently receiving around 400,000 doses of Pfizer per week, that is set to increase to nearly 800,000 doses per week in each week of May. Deliveries are expected to climb even higher to around 939,000 weekly doses in June.

As vaccine shipments increase, the age threshold for making an appointment through the provincial booking system is expected to be lowered as well. It is currently 60 and over in Toronto, but is lower in hot spot areas.

“As we move on, the age range will rapidly move lower and lower and lower,” Bogoch told CP24. “And in fact in May, we're expected to get way more Pfizer than we initially thought we were going to get and I think we're just going to start really clipping through the age groups and also the priority populations and priority neighborhoods at a much faster pace.”

As of Tuesday night, 3,782,486 Ontarians have had at least one vaccine shot.