CDC on Tuesday recommended the use of Novavax's protein-based Covid-19 vaccine in adults 18 and older, officially clearing a fourth Covid-19 vaccine for use in the United States.

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CDC signs off on Novavax vaccine

Following FDA's authorization of Novavax's vaccine last week, CDC's Advisory Committee on Immunization Practices (ACIP) on Tuesday similarly recommended the vaccine in a 12-0 vote. Later, CDC Director Rochelle Walensky endorsed the panel's recommendation, opening up the vaccine for use by the general public.

Unlike Pfizer-BioNTech's and Moderna's mRNA vaccines and Johnson & Johnson's adenovirus vaccine, the Novavax vaccine is considered more traditional. The Novavax option contains nanoparticles made up of proteins from the surface of the coronavirus. It requires two shots, 21 days apart, and is already authorized for use in several other countries.

In a clinical trial of more than 26,000 adults in the United States and Mexico, researchers found that two doses of Novavax's vaccine had an overall efficacy rate of 90.4% against symptomatic disease and an efficacy rate of more than 78% among adults ages 65 and older. However, experts expect that this level of protection may now be lower now since the vaccine was originally tested against older variants of the coronavirus.

"Novavax's COVID-19 vaccine, which will be available in the coming weeks, is an important tool in the pandemic and provides a more familiar type of COVID-19 vaccine technology for adults," CDC said. "Having multiple types of vaccines offers more options and flexibility for the public, jurisdictions, and vaccine providers."

In a statement, President Joe Biden commended the move to recommend Novavax's vaccine, saying it was "another step forward in our nation's fight against the virus."

"The science and data are clear: vaccines continue to protect people from serious illness, hospitalizations, and death—and with BA.5 increasing infections, it is essential that people get themselves and their kids vaccinated and stay up to date on their COVID-19 vaccinations," Biden said.

The Biden administration has already purchased 3.2 million doses of the Novavax vaccine, which is enough to fully vaccinate 1.6 million people. The doses are expected to be available to the public within the next few weeks.

Another option for the unvaccinated

So far, Novavax's vaccine has only been cleared for use as a primary series, instead of as a booster shot, meaning that it is only available to those who are unvaccinated. Currently, roughly 26 to 37 million U.S. adults are still unvaccinated against the coronavirus, and health experts say that they hope Novavax's more traditional vaccine will help convince those who remain skeptical.

"The primary target population for Novavax will be the 10% to 13% of those that are unvaccinated," said Oliver Brooks, a member of ACIP and CMO at Watts HealthCare Corporation. "I understand we're really focused on that population with the hope that perhaps this protein subunit vaccine will change them over from being unvaccinated to vaccinated."

However, survey data suggests that relatively few people who are still unvaccinated will decide to get Novavax's vaccine. According to data presented at ACIP's meeting, only 16% of unvaccinated respondents said they would "probably" or "definitely" get a protein-based Covid-19 vaccine. Similarly, a recent Morning Consult poll found that only 10% of unvaccinated respondents said they would definitely or probably get a protein-based vaccine.

"Optimism that the Novavax vaccine will have a significant impact on the number of unvaccinated Americans is misplaced," said Jason Schwartz, an associate professor at the Yale School of Public Health.

"A small number of people might have been waiting for a vaccine that doesn't involve mRNA technology or lacks the remote links to fetal tissue associated with the development of the currently available vaccines, but the vast majority of those unvaccinated have made their choice for unrelated and deeply ingrained reasons," he added.

What are Novavax's next steps?

In other countries, Novavax's vaccine has already been cleared for use as a booster shot and in children as young as 12. According to the company, it plans to seek U.S. authorization for the vaccine's use as a booster and in teenagers relatively soon, which will open it up to a broader population.

In addition, Novavax is testing a reformulated version of its vaccine targeted at the omicron variant ahead of potential new boosters in the fall and winter. According to preliminary data from laboratory and animal studies, a Novavax vaccine targeting the BA.1 omicron subvariant was able to generate a strong immune response to the virus.

Currently, a clinical trial of the reformulated vaccine is ongoing, and Novavax said it expects to have results by September, with doses becoming available in the last three months of the year. (Robbins/Zimmer, New York Times, 7/19; Howard/Dillinger, CNN, 7/19; Kimball, CNBC, 7/19; D'Ambrosio, MedPage Today, 7/19; AP/NPR, 7/19; Robbins/Zimmer, New York Times, 7/13)