How the vaccines we have — and the ones coming next — stack up against COVID-19 variants

How the vaccines we have — and the ones coming next — stack up against COVID-19 variants

by Sue Jones
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Infectious disease specialist Dr. Zain Chagla breaks down everything you need to know about the five leading COVID-19 vaccines and how they work — or don’t — against the variants of concern.

Covid Vaccinations

Health Canada has approved two COVID-19 vaccines, Moderna and Pfizer-BioNTech, and approvals on three more are expected in the coming months. (Evan Mitsui/CBC)


The Dose20:52What vaccines are coming next and how effective will they be against the COVID-19 variants?

While national-level COVID-19 data shows a downward trend in daily case numbers, eight provinces have reported patients infected with concerning new variants — the more transmissible strains of the coronavirus. 

Infectious disease experts say the B117 strain, originally found in the U.K., and the B1351 strain, originally found in South Africa, are as much as 50 per cent more transmissible. In Ontario, for example, public health officials have said B117 could be the dominant strain in a matter of weeks.

But Dr. Zain Chagla, an infectious disease physician for St. Joseph’s Healthcare in Hamilton, Ont., said there’s reason for hope.  He told Dr. Brian Goldman, host of The Dose and White Coat, Black Art, that he’s optimistic because five different vaccines have been submitted to Health Canada for approval, and each may play a role in controlling the variants. 

“A year ago I remember having meetings every day in the hospital saying, ‘When is this coming to Canada?’ ‘How are we going to handle it?'” said the associate professor of medicine at McMaster University. “How are we going to handle it? You know, seeing those apocalyptic images out of China and Italy, knowing that that was going to be here. And now, a year later, we’re … talking about five vaccines.

“The human spirit is incredible.”

Dr Zain Chagla

Dr. Zain Chagla, an infectious disease physician for St. Joseph’s Healthcare in Hamilton, Ont., and associate professor of medicine at McMaster University, says he remains optimistic the existing vaccines can fight the COVID-19 variants. (Craig Chivers/CBC)

Health Canada has approved two COVID-19 vaccines, Moderna and Pfizer-BioNTech, and three more may be approved in coming months.

Here’s how the five shots compare and what we know so far about how they fare in the fight against the more infectious variants. 

Pfizer-BioNTech & Moderna 

Both Pfizer-BioNTech and Moderna say their vaccines appear to be effective against both the B117 and the B1351 strains, based on blood samples from people who have been vaccinated. 

In a statement, Pfizer-BioNTech said these preliminary findings “do not indicate the need for a new vaccine to address the emerging variants.”

Chagla said, thankfully, both of these vaccines seem to be protective against B117 as it’s the variant spreading the most quickly in Canada.

However, as the clinical trials of both Moderna and Pfizer-BioNTech were completed before particular variants of concern took off, more research is needed to gather higher quality data.

Vaccine Efficacy Against Variants Graph

A comparison of the efficacy of the five leading COVID-19 vaccines against both the dominant strain of COVID-19 and two key variants, B117 and B1531. (Graphic by Ben Shannon/CBC)



In the final stages of review, the Oxford-AstraZeneca vaccine is expected to be the next formula approved by Health Canada. 

Chagla said the vaccine is about 70 per cent effective against the non-variant strain, based on late stage clinical data released by AstraZeneca.

The news isn’t so great when it comes to the variants. This week, South Africa paused part of its rollout of the AstraZeneca vaccine after data from a small trial showed it did not protect against mild to moderate illness from the B1351 variant now dominant in the country.

But Chagla said it’s important to put this news in context, and that more research is needed. 

“You still don’t have good news or bad news in terms of if these vaccines still prevent hospitalizations and death,” he said.

If it turns out the vaccine does a good job of preventing severe cases, “it could still be a useful intervention there,” Chagla said.

On Wednesday, a World Health Organization panel said the vaccine is safe and effective and should be used widely, even in countries where the B1351 variant is dominant. 

Johnson & Johnson

Johnson & Johnson submitted its one-shot vaccine for approval in the U.S. last week. 

The company says its Phase 3 clinical trial data showed the vaccine is overall 66 per cent effective at preventing moderate to severe COVID-19.

Chagla said there’s a lot of hope with this vaccine, despite the lower overall efficacy rate compared to Moderna and Pfizer-BioNTech’s vaccines which have around 95 per cent efficacy.

He said the fact that it can be kept in a regular fridge and is administered in just one dose means the Johnson & Johnson vaccine could be a game-changer. 

“It may not be as efficacious as Pfizer, but perfection is the enemy of good,” Chagla told Goldman.

“If we had the entire Canadian population have a dose of Johnson & Johnson tomorrow, knowing that in 40 days, most people would not be hospitalized or die from COVID-19, I think all of us would breathe a huge sigh of relief.”

WATCH | Why the single-shot logistics of Johnson & Johnson’s vaccine matter:


Calling the clinical trial ‘thorough,’ infectious disease specialist Dr. Matthew Oughton says Johnson & Johnson’s single-shot COVID-19 vaccine is also easier to handle logistically compared to approved vaccines in Canada. 3:40


Novavax is a two-dose vaccine that can also be stored at regular fridge temperature.

The company said early findings from U.K. research show its vaccine appeared to be 86 per cent effective against B117 and 60 per cent effective against B1351.

“This is an incredibly important vaccine for both [U.K. and South African] settings and very, very promising for B117, as well as what’s circulating here in Canada normally,” said Chagla.

Canada has signed an agreement for Novavax to produce tens of millions of doses of its COVID-19 vaccine in Canada once it’s approved by Health Canada.

No ‘best’ vaccine

In a few months, Canada may have five different vaccines going into arms, and Chagla said there is no one “best” vaccine among them.

“The best vaccine is the one that’s administered. Every Canadian should be hopeful that they can get one of these vaccines, period.”

Chagla said the next few months are critical. Until enough people have got their shots, Canadians need to hang tight and continue to socially distance, stay home as much as possible, wear masks and follow public health guidelines. 

But he’s optimistic better days are coming. 

“Hopefully, we can talk about a summer and a fall that is getting back to normal.”

Written and produced by Willow Smith 

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