Here’s Why the Novavax Vaccine Is So Different From the mRNA Options

It’s been a year and a half since the U.S. Food and Drug Administration (FDA) authorized a new COVID-19 vaccine. But now, Americans have another option to consider: The FDA has officially authorized the Novavax COVID-19 vaccine for emergency use in the U.S.

The Novavax vaccine is the fourth COVID-19 vaccine option available to Americans. Two vaccines—manufactured by Pfizer-BioNTech and Moderna, respectively—were approved for use following their individual authorizations, while the Johnson & Johnson COVID-19 vaccine is still operating under an emergency use authorization with restrictions.

The Novavax vaccine is authorized for use in people ages 18 and up—and the Biden administration has already ordered 3.2 million doses of it, which is enough to vaccinate 1.6 million Americans.

According to data from the Centers for Disease Control and Prevention (CDC), the number of new COVID-19 vaccinations in the U.S. has stalled a bit—but some experts are hopeful that another option might help boost that number. So, here’s what you should know about Novavax, including how this particular vaccine works and why it’s pretty different from its mRNA counterparts.

How does the Novavax vaccine work?

Like the Pfizer-BioNTech and Moderna COVID-19 vaccines, the Novavax vaccine is administered in two doses, per the FDA. With Novavax, each vaccine is spaced three weeks apart. (Worth noting: Novavax hasn’t been authorized as a booster vaccine yet—just an original series.)

However, the Novavax vaccine isn’t an mRNA vaccine like Pfizer’s and Moderna’s options; these use messenger RNA (which carries information from the DNA in a cell’s nucleus) that is created in a lab to teach the body how to create an immune response, per the CDC. Novavax is actually a protein-based vaccine, with no mRNA required. 

Here’s how it works: To create the vaccine, scientists use the spike protein from the genetic sequence of SARS-CoV-2, the virus that causes COVID-19. This spike protein is what allows the coronavirus to latch onto and enter human cells. The researchers then take this modified spike protein gene and insert it into a baculovirus (a.k.a. an insect virus), per the FDA. That virus is then used to infect insect cells. New spike proteins grow, which are then harvested and used to mimic SARS-CoV-2 to set off an immune response (meaning it cannot actually make you sick). Once you receive the vaccine, your body then perceives the altered proteins as a threat and produces antibodies that can then jump into action should you be infected with COVID-19 in the future. The vaccine also includes an adjuvant, which is an ingredient used in some vaccines to help create a stronger immune response, the CDC explains.

Like any vaccine, the FDA says you may experience short-lived side effects following your dose, including pain or swelling at the injection site, fatigue, headache, fever, and generally feeling unwell as your body ramps up its immune response.

How effective is the Novavax vaccine?

The Novavax vaccine is up to 90.4% effective at preventing COVID-19, according to data from a 2021 phase 3 clinical trial published in the New England Journal of Medicine. “Of the two phase 3 trials, both found that the efficacy of the vaccine against mild, moderate, and severe disease is 90%,” the World Health Organization says. (However, it’s important to point out that the Novavax vaccine was studied from December 2020 through September 2021, before the dominant, highly infectious omicron subvariants, like BA.5, were circulating.)

Why is it important to have another vaccine option right now?

At this point, it may feel like people who want to get the COVID-19 vaccine would have done it already, but health experts say having even just one more option is a positive step forward in our pandemic response.