Health·CBC Explains

How the Novavax COVID-19 vaccine differs from those already approved in Canada

The Novavax vaccine, now closer to joining Canada's COVID-19 inoculation program, differs from the two vaccines Canadians are currently receiving to guard against the respiratory illness, primarily because of the way it's engineered to induce an immune response in the body.

Ottawa has tentative deal to make millions of doses of vaccine candidate in Canada

U.S.-based company Novavax has developed what's called a recombinant protein vaccine. It says harmless copies of the coronavirus spike protein were grown in insect cells. Scientists extracted and purified the protein and then mixed in an immune-boosting adjuvant. (Phil Noble/Reuters)

The Novavax vaccine, now closer to joining Canada's COVID-19 inoculation program, differs from the two vaccines Canadians are currently receiving to guard against the respiratory illness, primarily because of how it's engineered to induce an immune response in the body.

It's a protein subunit vaccine, meaning it uses nanoparticles of a lab-grown spike protein that mimics the natural spike protein on the surface of the novel coronavirus and which helps the virus bind to cells and cause infection.

When the particles are injected into the body with an adjuvant — a compound that enhances immune response — the body learns to recognize and fight off the virus.

Protein subunit vaccines don't elicit as strong an immune response as whole virus vaccines, so they often include an adjuvant. Novavax uses a proprietary adjuvant called Matrix-M, which is based on a type of compound found in many plants called a saponin. The company says it boosts the body's immune response and generates a bigger immune response with a lower dose.

The tried-and-true method of making a custom copy of a virus spike protein has been used to develop vaccines against HPV, hepatitis B and influenza.

The Moderna and Pfizer-BioNTech vaccines, on the other hand, use a newer approach.

Both use messenger RNA (ribonucleic acid) technology, or mRNA, which the Centers for Disease Control says has been studied for more than a decade.

Those vaccines give genetic instructions to the cell on how to make a piece of the spike protein that is unique to the virus that causes COVID-19.

Maryland-based Novavax says its two-dose vaccine, which will be administered 21 days apart, remains stable at 2 C to 8 C, meaning it only needs basic refrigeration.

Pfizer's vaccine needs to remain frozen before use at –70 C, while Moderna's vaccine needs to be stored at –20 C. Official guidelines say doses of the Pfizer-BioNTech vaccine should be given 21 days apart, while Moderna recommends spacing shots 28 days apart.

Early findings from U.K. research show the Novavax vaccine appeared to be 86 per cent effective against a new variant of the virus first reported in Britain and 60 per cent effective against the variant circulating in South Africa, the company said on Jan. 28. The efficacy against the original strain of virus that causes COVID-19 is thought to be around 95.6 per cent.

WATCH | Officials provide update on vaccine deliveries to Canada:

Public health officials provide update on COVID-19 vaccine deliveries to Canada.

1 year ago
Duration 2:41
Maj.-Gen. Dany Fortin briefed reporters in Ottawa Thursday on Canada's vaccine procurement and distribution program.

Prime Minister Justin Trudeau says Canada has signed a tentative agreement for Novavax to produce tens of millions of doses of its COVID-19 vaccine in Canada once it's approved for use.

Novavax is still conducting clinical trials, but if Health Canada approves the vaccine, a new National Research Council-owned facility in Montreal will begin pumping out doses when the building is finished later this year. It would be the first COVID-19 vaccine to be produced in Canada.


Innovation Minister François-Philippe Champagne says the Montreal facility should be in a position to produce the vaccine "by the end of the year."

Novavax has said it plans to develop a new vaccine aimed specifically at the variant found in South Africa. 

WATCH | Growing concern about COVID-19 variants in Canada:

Growing concern about COVID-19 variants in Canada

1 year ago
Duration 4:16
COVID-19 numbers are falling, but Canadian health officials are becoming increasingly concerned about the presence of two coronavirus variants. A variant first found in the U.K. has been confirmed in three provinces while a variant first discovered in South Africa variant has been found in two provinces.


  • An earlier version of this story said the Novavax vaccine's efficacy against the original strain of virus was thought to be 89 per cent. It is 95.6 per cent.
    Feb 03, 2021 10:42 AM ET

With files from CBC's Emily Chung

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