Is it OK to mix vaccines? Regional, provincial health officials say yes

Health officials are assuring anyone concerned about mixing COVID-19 vaccines that there's not much difference between Pfizer-BioNTech and Moderna, and getting either if a person had AstraZeneca first is also OK.

Concerns have been raised on social media over news the Region of Waterloo Public Health vaccine clinics will only have Moderna for people 18 years old and up for a few days due to delay of shipping the Pfizer-BioNTech vaccine to Canada.

Dr. Hsiu-Li Wang, the region's medical officer of health, asked anyone who has an appointment to get a first or second dose in the coming days to "please keep it."

"These mRNA vaccines are from different manufacturers but they are essentially identical twins," Wang said in a release on Sunday. "We want everyone to be protected from COVID-19 as soon as possible and we need to halt the spread of the delta variant in Waterloo region."

The delta variant is also known as B.1.617.2 and was first detected in India. Wang has said it's believed to be circulating widely in Waterloo region and is the reason for a high number of new COVID-19 cases over the past week.

All approved vaccines will protect you

Dr. Nicola Mercer, CEO and medical officer of health for Wellington-Dufferin-Guelph Public Health, also warned the delay in Pfizer-BioNTech vaccines will impact those communities.

"We must do what we can to ensure we continue to vaccinate our region as quickly as possible. I want to assure residents of Wellington-Dufferin-Guelph that their first or second dose will be safe and effective," Mercer said in a release on Monday.

Young people between ages 12 and 17 will still have access to Pfizer-BioNTech, though, as Moderna is not yet approved for use in Canada in people under age 18.

Earlier this month, the National Advisory Committee on Immunization (NACI) updated its guidance to provinces and territories recommending the safe mixing and matching of second doses of COVID-19 vaccines.

In a tweet, Ontario Health Minister Christine Elliott also said the two mRNA vaccines are similar.

"If you had Moderna or Pfizer for your first dose, you can safely take either for your second," Elliott wrote. "If you had AstraZeneca for your first dose, you can safely take AstraZeneca, Moderna or Pfizer for your second. All vaccines provide strong protection against COVID-19 and its variants."

A spokesperson for Elliott told CBC Toronto the Pfizer-BioNTech vaccine delay is expected to be two to three days, although it's unclear what that means on a local level in Waterloo region or Wellington-Dufferin-Guelph.

'Essentially the same'

In the past, clinics in the region have seen people walk away from the Moderna vaccine.

Pharmacist Kelly Grindrod says the difference between Moderna and Pfizer-BioNTech is only that they are made by different companies.

"What we're seeing is, over and over in studies, it's the same effectiveness, same efficacy, same side-effects," she said in an interview. "These two vaccines are essentially the same vaccine — just different brands of the same thing."

Grindrod said if anything, Moderna is actually the easier one to use for those giving the vaccines because it doesn't need to be kept in ultra-cold freezers or be diluted like the Pfizer-BioNTech vaccine, which means fewer steps needed to get the vaccine into people's arms.

Moderna has been widely used in the United States, and Grindrod says it has an interesting backstory: Country singer Dolly Parton donated $1 million into research for the vaccine and a young Black scientist, Kizzmekia Corbett, 34, was a key Moderna developer.

Clinics worried people will walk away

Grindrod is an associate professor of pharmacy at the University of Waterloo and runs a vaccine clinic at the School of Pharmacy at King and Victoria streets in Kitchener. She says health officials in the region fear people will attend a vaccine clinic, find out they're getting Moderna and then walk away.

With the increased risk of the delta variant, people really need to make sure they get two shots, she said.

"If we start having no-shows, those are appointments, those are doses that people didn't get," she said.

"People think of it as waiting for a few days … people think about it as their own, individual decision, but they're actually one person in tens to hundreds of thousands that we have to get the vaccine to. And so much of this concern is actually because they just don't know, or don't realize or don't understand or haven't been told Pfizer and Moderna are essentially the same vaccine," she added.

"For most people, they would say, 'I'd never walk away from Pfizer,' but that's exactly the thinking that should apply here for Moderna."