What’s different about the Novavax vaccine?


Novavax’s vaccine is the newest player on the U.S. landscape. Public health folx are hoping that its approach will reassure some people who are otherwise hesitant about COVID-19 vaccines.

Novavax’s vaccine is the newest player on the U.S. landscape. Public health folx are hoping that its approach will reassure some people who are otherwise hesitant about COVID-19 vaccines.

Unlike all the other vaccines on the market so far, this vaccine does *not* recruit our cells to temporarily make the all important spike protein. Instead, it simply contains the spike protein of SARS-CoV-2, which is grown in cultured moth cells and then isolated and purified in a lab. It does not contain the whole virus, so it can’t cause an infection. This is a tried-and-true approach to vaccine manufacturing, though the moth cell culture is an innovation.

Novavax also contains an adjuvant, which is something added to a vaccine to stimulate a stronger response from the immune system. The Novavax adjuvant is unique too. It’s a compound derived from tree bark.

Other advantages: Novavax is cheaper to manufacture and can be stored in a refrigerator, which means it’s very helpful in lower-resourced and remote settings globally.

The CDC will meet next week to discuss who can get this newest vaccine in the United States, and it’s likely to be all adults. The U.S. has purchased 3.2 million doses which will be distributed as soon as the CDC makes a recommendation, so it should be on shelves in the next week or so.

The vaccine is given IN two doses, 3 weeks apart. Given everything we’ve learned about COVID-19 vaccines, yes: this one will very likely also need a booster down the road. CDC may also recommend that severely immunosuppressed patients get a third dose in their primary series. We’ll see soon. WHO does recommend the extra dose.

In the clinical trial data that were reviewed by the FDA, about 17,200 adults got the vaccine and another 8,300 got a placebo. Novavax had 90.4% overall efficacy at preventing mild, moderate, and severe COVID-19 of all variants, in all groups. It was 100% effective at preventing moderate or severe COVID-19. 100% means there were zero hospitalizations in participants who got the vaccine. There were 14 in the placebo group. The study was conducted before Omicron but after Alpha, Beta, and Delta variants.

Participants tolerated the vaccine well. Side effects following the first dose were limited to sore arm and a little bit of tiredness. Side effects were higher after the second dose, but still lower compared to mRNA vaccine side effect rates. For example, 44% of the people in the Novavax trial vaccine group reported a headache after their second dose. (But 22% of people in the placebo group also reported a headache). 6% reported fever after dose 2 (vs. less than 1% in the placebo group).
Myocarditis could be a rare adverse effect for Novavax, as for other COVID-19 vaccines. Four cases of myocarditis occurred within 20 days of vaccination in the trial. As with all of the COVID-19 vaccines on the market, this side effect is very rare and the risk is highest in adolescent/young men.

We have to emphasize again that myocarditis risk is *way* higher when young people get COVID-19. Not vaccinating is also a decision–and it puts you at a much higher risk of myocarditis.

Novavax is new on the U.S. landscape, but it’s been approved and in use for months in over 40 other countries. Millions of people have received it already, and there have been no major safety issues.

Some more info here:

FDA: Coronavirus (COVID-19) Update: FDA Authorizes Emergency Use of Novavax COVID-19 Vaccine, Adjuvanted

STAT News: FDA authorizes Novavax Covid vaccine, in hopes the traditional shot will convince holdouts

WHO: The Novavax vaccine against COVID-19: What you need to know

Our recent posts on Novavax:

Meet Novavax, Which May Be the US’ Next Authorized COVID Vaccine

Novavax Vaccine Update!

Update on Novavax

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