EXPLAINER: How does the Novavax vaccine work?

The Novavax vaccine was approved for use in Canada on Feb. 17, adding yet another vaccine to the country’s arsenal in the fight against COVID-19.

The vaccine dubbed Nuvaxovid is protein based — the first of its kind to be approved in Canada.

How does Novavax work compared to Pfizer or Moderna?

Compared to Pfizer and Moderna’s mRNA vaccines that use newer technology, Nuvaxovid relies on a more traditional method of eliciting an immune response from the body.

Infection control and infectious disease physician Dr. Alon Vaisman explains that most vaccines are made out of some component of the virus or bacteria itself.

“For example, if you were to get a meningococcal vaccine, you’re getting a little piece of the cell wall of the bacteria. In this case, we’re getting a little piece of the protein that the virus produces,” he said.

In comparison, the mRNA vaccines contain the genetic code for that protein. The body then makes the protein, which in turn triggers the immune system to attack it as an unknown entity.

“[Nuvaxovid] goes one step beyond what the mRNA vaccine would do. Instead of using our own body’s machinery to create that protein, this vaccine just gives it to us and shows our immune system the foreign antigen, which is what we use to create our antibodies. So it says ‘here’s what it looks like, produce the antibodies to this. Next time you see something like this … you should attack it,” explains Vaisman.

Is Novavax better than Pfizer of Moderna?

Dr. Vaisman says it is a common misconception that the vaccine that took longer to develop and uses an older method may be more reliable.

“There isn’t a lot of validity to say that Novavax is a ‘traditional one’, so to speak, and therefore we can rely on it more,” he said.

He adds that many may have felt that the newer mRNA vaccines weren’t tested thoroughly enough or were somehow unsafe, but that is not the case. They were first out the gate simply because the genetic sequence of the virus was determined very early on in the pandemic, making it possible to develop a vaccine based on that information.

“All vaccines that are approved now in Canada have gone through rigorous testing and are all safe,” Vaisman reiterated.

“If anything, mRNA vaccines have a lot more experience than any vaccine we’ve ever dealt with. Hundreds of millions of people [have gotten] mRNA vaccines by now — that’s far more data we’ve had in such a short time than probably any vaccine we’ve ever had. The vaccines we’ve had for the last 50-60 years — lots of people have gotten those, but it’s over a very long period of time. Here we have so much data piling up very quickly,” he added.

Vaisman says the mechanism by which the vaccine works is also not an indicator of efficacy.

“There isn’t any specific reason why you might choose one for another, except if you have some kind of personal preference. But in terms of how it works, not necessarily,” he said. “I think the overall question about which vaccine is right for people is not going to be based on preference. It is going be based on hard data.”

Vaisman cites the flu vaccine as an example, saying that there are usually a variety of formulations of it. The one you get isn’t based on your preference, but what the data shows about how well it works in various age groups.

“So we give a certain formulation to children, to middle aged people, and then to seniors, because we know that certain formulations work better [for them],” he explained.

Clinical studies show that Nuvaxovid is 90 per cent effective against severe disease and 100 per cent effective against death from COVID-19.

“This vaccine looks really good. How it works in the real world will depend on how it works on the variants and when we see it rolled out in large numbers,” he said.

Will Novavax be effective against COVID-19 variants?

Dr. Vaisman says it is too early to know whether Nuvaxovid will be as effective against new virus variants.

“We saw that with mRNA vaccines … as new variants developed, its protection against symptomatic disease was reduced, but it maintained a very high level protection against severe outcomes like death,” he said.

With the current mRNA vaccines, if the protein in the virus has not mutated drastically in a new variant, additional doses of the same formulation afford additional protection.

It is unclear if new formulations of Nuvaxovid will be required to combat new variants.

“It will probably depend more on what we see in real world data,” said Vaisman.