Peel’s top public health official is urging residents to get their second dose of COVID-19 vaccine “as soon as possible” amid reports that some individuals have “walked away” from appointments after being told that they would receive a different shot than they did for their first dose.

A delayed shipment of the Pfizer vaccine meant that city-run clinics in both Toronto and Peel Region had to mostly shift to administering Moderna this week, while setting aside the limited remaining supply of Pfizer for children 12 and up.

The National Advisory Committee on Immunization (NACI) has stressed that both Pfizer and Moderna are mRNA vaccines and that there is “no important difference” between the two, however there have nonetheless been anecdotal reports of people refusing to receive Moderna for their second dose.

That, in turn, has led to concerns that future shipment delays involving Pfizer could slow the administration of second doses, even as the supply of Moderna continues to ramp up.

Canada, in fact, is expected to receive 2.8 million doses of the Moderna vaccine this week alone.

“Some residents with dose two appointments booked for this week have actually refused Moderna and walked away. That's the equivalent of saying that you won't fly with an airline because it's not your preferred airline that has seats off an island that is sinking. You'd rather wait for the next available seat on your preferred airline, which could be weeks away,” Peel’s Medical Officer of Health Dr. Lawrence Loh said during a briefing on Wednesday morning. “I cannot say this clearly enough. Please take whatever you are offered.”

City-run clinics have predominantly administered the Pfizer vaccine to date but as the supply of Moderna increases, they are starting to shift their approach to more widely use both mRNA vaccines.

Loh said that “further reductions” in Pfizer supply are also expected in July, underscoring the importance of mixing and matching vaccines going forward.

“For anyone who's refusing a vaccine to hold out for another, know this: you're leaving yourself partially unprotected, your family partially unprotected and you're prolonging our reopening,” he said. “While our vaccine supply has improved, it remains finite. We aren't at a point yet where we can be picky. We need to protect our community with everything we've got. Previous stocks of Pfizer helped us get to our one dose coverage goal. Now our Moderna supply is growing quickly and that will help us get to our two dose coverage goal and get to the end of all of this. But in order to do so I need you to remember that mRNA is mRNA.”

While Loh indicated that Peel Region is encountering some instances of individuals refusing the Moderna vaccine, officials in Toronto have largely dismissed the issue as being a significant contributor to hesitancy.

At a briefing earlier on Wednesday morning, Toronto’s vaccine task force chair Matthew Pegg said that the total number of people who are declining a vaccine after arriving for an appointment is “very, very low” and is not having a significant impact on the number of shots being administered.

“The information I have from our teams on the ground yesterday is no significant issue at all. The staff were happy, the clients were happy and the level of service across the networks and clinics was fantastic with ore than 16,000 people being vaccinated,” he said.