Novavax COVID-19 vaccine approved for use in Canadian adults

Novavax’s COVID-19 vaccine has been approved for use in adults aged 18 years of age and older in Canada.

Health Canada updated the list of approved COVID-19 vaccines on Thursday to include Novavax’s product. Pfizer, Moderna, AstraZeneca and Johnson and Johnson are the other vaccine makers that have COVID-19 jabs approved for use in Canada.

Speaking during a technical briefing Thursday, Canada’s chief medical adviser Dr. Supriya Sharma said that the Novavax vaccine was shown to have 90 per cent effectiveness at preventing symptomatic COVID-19 and 100 per cent effectiveness at preventing severe disease.

This efficacy data is “based on studies conducted during earlier waves of the pandemic,” Sharma said. “Preliminary data available at this time suggest that the vaccine also produces neutralizing antibodies against the Omicron variant, but more data is still needed as a condition associated with the authorization.”

Novavax’s two-shot Nuvaxovid vaccine was not approved for use in people under 18 as its safety and effectiveness in younger people have not yet been established.

Health Canada recommends two doses of Nuvaxovid be given 21 days apart, based on evidence from clinical trials.

According to Canada’s chief public health officer, Dr. Theresa Tam, the availability of this new vaccine can “help remove barriers to vaccination by providing an additional option to adults who have not yet received a COVID-19 vaccine at this time.”

“The Novavax vaccine may be offered to individuals who are unable or unwilling to receive a mRna vaccine,” Tam said, at the same news conference.

1:59 Montreal facility to produce Novavax vaccine in the fight against COVID-19

“It is not currently authorized for use as a booster dose, but it may be offered as a booster to individuals who are unable or unwilling to receive a mRna vaccine, regardless of which COVID-19 vaccine they received for their primary series,” she said.

However, that would have to be an “off-label use” according to Tam. “Informed consent would be needed, of course, to discuss the benefits and risks with the individuals who are getting that booster,” she added.

A major hurdle Canada has faced in its vaccine rollout is the fact that there’s no capacity to produce COVID-19 vaccines within the country.

In February 2021, Prime Minister Justin Trudeau announced that the government had secured a tentative deal with Novavax to allow the National Research Council-owned Royalmount facility in Montreal to produce its vaccine once it gets approved for use in Canada.

Canada has committed to purchasing 52 million doses of the vaccine, with an option to buy up to 24 million more doses. The first shipment is expected in March but it would be not be coming from the Montreal facility. Instead, it would be procured from India’s Serum Institute, according to Dr. Tam, who also added that there’s no clear timeline for when production of the vaccine could begin in Canada.

The Novavax COVID-19 vaccine is the first protein-based vaccine to be offered in Canada as part of a two-dose regimen of five mcg per dose. These vaccines contain a modified version of the spike protein itself, unlike mRNA vaccines that have molecular manufacturing instructions for the body to make the spike protein.

According to Sharma, the protein vaccines contain “small pieces of viral protein that have been specifically selected for their ability to trigger immunity.”

These vaccines have the same objective as the other COVID-19 vaccines, “which is to expose a person’s immune system to the SARS-CoV-2 spike protein and activate the immune system to make antibodies to neutralize it the next time the person is exposed to the virus,” Sharma explained.

1:11 Health Canada advisor on the difference between protein-based and mRNA vaccines

However, the approach is different.

The mRNA vaccines instruct our cells to make a specific protein that’s found in the SARS-CoV-2 virus that causes COVID-19. When the cells make that protein, the immune system gets trained to recognize it, building antibodies that help fight off COVID-19.

Sharma also clarified that these protein subunit vaccines “cannot cause COVID-19 because they only contain small, purified pieces of proteins and not the virus itself.”

Such vaccines are already used for other diseases, such as hepatitis B, pertussis and influenza, Sharma added.

Novavax’s protein-based vaccine is still being reviewed by the U.S. Food and Drug Administration but has received approvals from the European Union and the World Health Organization.

It has also been cleared for use in adults in countries including the United Kingdom, New Zealand and Australia.

While additional confirmatory data is needed, Health Canada says preliminary and exploratory data shows that Nuvaxovid produces neutralizing antibodies against the Omicron variant.

However, Sharma said that Novavax is required to provide Health Canada with data on “protection against current and emergency variants of concern as it becomes available.”

“I know there are likely some questions regarding the effectiveness of this vaccine compared to the many vaccines. However, comparing vaccines is challenging, as its clinical trials were not designed to test the vaccines against each other,” Sharma added. “That said, all authorized vaccines have been shown to be very effective at preventing what matters most and that serious illness of COVID-19.”

Tam agreed.

“No vaccine is 100 per cent effective,” said Tam. “So, keep layering up by wearing high quality, well-fitting masks or respirators, avoiding crowds and improving indoor ventilation (to) reduce your risk of COVID-19.”

The common side effects of Novavax’s two-shot Nuvaxovid vaccine include “pain and tenderness at the injection site, headache, muscle pain, fever and chills,” according to Sharma.

“These side effects are typical with most vaccines across all clinical trials of the vaccine,” she said.

But “two cases of myocarditis appear to be associated with the vaccine,” Sharma added. “Both occurred in young men after their second doses.”

Two other cases possibly associated with the vaccine have also been reported.

“However, these participants were also dealing with severe acute infections that were more likely to be the cause,” Sharma said. “Three cases were clearly unrelated to the vaccine.”

The initial data, Sharma explained, suggest that the potential risk of side effects is “very, very rare and the benefits of the vaccine continue to outweigh its risks in all age groups.”

— with files from Rachel Gilmore and Reuters