KITCHENER -- Hundreds of people in Waterloo Region don't know when they'll be able to receive a second dose of the AstraZeneca vaccine due to a supply shortage.

Brian Stoddard received his first dose on April 5 at a local pharmacy. His second dose is booked for July.

"All I know at this point is that I have an appointment, but I don't have anything to confirm that," Stoddard said.

Nancy McCurdy got her first dose four weeks ago.

"It seems like there are certainly some issues with the distribution," she said.

Many pharmacies across the region have run out of AstraZeneca shots and said they don't have any new deliveries confirmed at this time.

"We don't have any vaccine, honestly, to give," pharmacist Gurinder Brar said.

The shortage has created uncertainty for people hoping to book an appointment for a second dose.

"We are already getting hundreds of calls every day and I imagine if you don't have that, there will be chaos," Brar said. "I'm very hopeful we will get it, but again I have a little bit of fear in my mind."

On Tuesday, Procurement Minister Anita Anand said Canada is expected to receive 2 million doses of AstraZeneca by the end of June, adding around one-quarter of that is expected "in the next number of weeks."

"We will continue to press the supplier as well as other sources for an expedited delivery of AstraZeneca into this country," Anand said.

Pharmacists said the uncertainty is frustrating.

"I have patients calling me and I don't really have a good answer," pharmacist Scott McDonell said.

It's also unclear if people who received a first dose of AstraZeneca could opt for a second dose of a different vaccine.

Research out of the U.K. suggests the second vaccine could be different than the first and studies are still looking at whether or not people can mix vaccines.

"To see whether you can go with AZ and then go with Pfizer as a second dose or Moderna and mixing and matching them," McDonell said. "I think the general expert opinion is it's probably safe."

Canada's top doctor said Tuesday they're still waiting to see more research data.

Some pharmacies in the GTA are piloting the Pfizer vaccine and local pharmacists said they'd be happy to do so as well, but it's not yet known if and when that might happen.