Clinical trial data shows the shot to be highly effective with fewer side effects than other vaccines available in the U.S. Key TakeawaysAn FDA panel voted to recommend the authorization of Novavax’s COVID-19 vaccine in the United States.Novavax uses a protein-based technology, a more traditional approach than the novel technologies used by other vaccine
A panel of advisers to the Food and Drug Administration (FDA) voted to recommend the authorization of Novavax's two-dose COVID-19 vaccine after evaluating its safety and effectiveness today.
Novavax is a latecomer to the U.S. vaccine program. If the FDA and the Centers for Disease Control and Prevention sign off on the vaccine, it will be the fourth COVID-19 vaccine available to people in the U.S.
The Novavax vaccine uses a protein-based technology, which is more traditional than the new mRNA technology used by Pfizer and Moderna. The formula held promise early in the pandemic when early phase trials indicated its high efficacy. Now, the U.S. is flush with vaccine supply, and more than 70% of Americans older than 5 are fully vaccinated.
Still, the FDA panelists determined that Novavax offers an option for people who remain hesitant to receive an mRNA vaccine, such as Pfizer's or Moderna's, or the Johnson & Johnson shot.
“We do have a problem with vaccine uptake that is very serious in the United States,” said Peter Marks, MD, PhD, director for the FDA's Center for Biologics Evaluation and Research. “Anything we can do to get people more comfortable to be able to accept these potentially life saving medical products is something that we feel we are compelled to do."
The company presented data showing the vaccine has an efficacy of about 90.4%. The findings come from two large clinical studies conducted in 2021 and involving more than 44,000 people.
Notably, neither of these studies were conducted while Omicron was circulating in the U.S.
The Novavax vaccine, called NVX-CoV2373, is already authorized in more than a dozen countries and by the European Commission and the World Health Organization.
The two-dose regimen consists of two half-milliliter doses given 21 days apart.
In a phase 3 clinical trial in the U.S. and Mexico, the company found that a two-dose regimen of the vaccine conferred 90.4% protection against infection and 100% efficacy against moderate and severe cases of COVID-19. A second phase 3 clinical trial, which included more than 14,000 participants in the U.K., found it to have 89.7% efficacy.
Data in both trials were collected before the Omicron surge. The company hasn’t yet collected data on how its vaccine holds up against Omicron.
The panelists said the data presented by Novavax was consistent with the study findings from Moderna and Pfizer when they requested authorization for their vaccines in 2020.
Diana Florescu, MD, professor of medicine at the University Nebraska Medical Center, led a portion of the clinical trials for Novavax. She said she expects the vaccines to hold up against current and future variants of concern.
“It's most likely that there is a decrease in protection with the variants,” Florescu told Verywell. “[Omicron] would probably increase the number of patients with milder disease or perhaps moderate disease, but [the vaccine] will still protect against severe disease and hospitalization.”
The company reported mostly mild and moderate side effects that resolved within a day or two. The most common were injection site tenderness, headache, nausea, muscle pain, joint stiffness, and fatigue. In the larger phase 3 clinical study, there were no cases of severe allergic reaction, vaccine-induced thrombosis, or Guillain-Barre syndrome.
Of 40,000 participants, there were six cases of myocarditis and pericarditis. Representatives from Novavax said this number is consistent with the rate of myocarditis in the general population and that there is not enough evidence to indicate that the vaccines caused the rare forms of heart inflammation.
While some of the FDA panelists said more data ought to be collected on the association between the vaccine and myocarditis, they determined the benefits outweighed the risks of vaccination overall.
“There appears to be a causal association with the Novavax vaccine, but there appears to be a causal association with the messenger RNA vaccines also,” said Cody Meissner, a panelist and professor of pediatrics at Tufts University. “I don’t want to stigmatize this vaccine inappropriately, relative to the mRNA vaccine.”
When COVID-19 first emerged, Novavax scientists singled out the virus’s spike protein and created a modified version of it.
Unlike the other authorized vaccines, which deliver genetic material to direct protein production by the cells, the Novavax vaccine delivers proteins directly. The antigen in the vaccine cannot replicate, nor can it cause COVID-19.
There are four main types of COVID-19 vaccines in development: mRNA, vector, protein subunit, and whole inactivated virus vaccines. The mRNA vaccines by Pfizer and Moderna were the first to be approved by the FDA. Johnson & Johnson’s adenovirus vector vaccine is also authorized in the U.S.
This approach, called recombinant nanoparticle technology, is more traditional to vaccine development, compared to the novel mRNA and adenovirus vector technologies.
Recombinant protein sub-unit technology has been used safely for decades. For instance, the hepatitis B vaccine, licensed in 1986, is recommended for all newborn U.S. babies. The human papillomavirus vaccines have been crucial for minimizing cervical cancer since 1991.
Florescu said that because Novavax vaccine employs a tried-and-true vaccine technology and presents a relatively low risk of developing side effects, making it available in the U.S. “will make a big difference.”
“I got pretty sick with the vaccine I received, and my daughter was the same. We are both saying, 'Well, next time we'll get Novavax—perhaps we're not going to get so sick,” Florescu said. “To be honest, I think I would like to have this vaccine next time.”
The U.S. is awash in COVID-19 vaccines. Still, many remain unvaccinated.
Florescu, who led some of the Novavax trials, said that many participants asked when the vaccine would be approved. "They have family members who did not receive any other vaccine and want a traditional vaccine," she said.
Gregory Poland, director of the Mayo Clinic’s Vaccine Research Group and a paid consultant to Novavax, presented on the clinical need for the protein-based vaccine. He cited a February poll indicating that 73% of Americans “would like to see additional COVID-19 vaccines that are developed from a more traditional method.”
“It’s important to have choices in vaccine platforms in a pandemic that is constantly evolving,” Poland said.
But not all panelists agreed that introducing another vaccine so late in the game would substantially improve uptake.
“I'm a little skeptical about how many of the vaccine hesitant are just waiting for this vaccine and are going to be convinced that this is better for them than the vaccines that are currently available,” Arthur Reingold, a panelist and professor of epidemiology at Univeristy of California Berkeley, said. “On the population level, I'm hoping to be proven wrong.”
In 2020, the federal government awarded Novavax a $1.6 billion contract to produce 110 million doses of its vaccine.
But manufacturing difficulties hampered the creation and roll-out of the vaccine. Because manufacturers must make both the engineered spike protein and the adjuvant, the vaccines take longer to develop. In 2020, Science reported that Novavax didn’t own its own manufacturing equipment at the beginning of the pandemic, causing manufacturing slow-downs.
Florescu said Novavax is in the midst of testing booster shots in clinical trial participants who’ve received the primary two-dose regimen. Some of those participants have already received additional doses from other vaccine manufacturers. Florescu said collecting data on their outcomes will help scientists understand the safety and effectiveness of mixing and matching the Novavax shot with other vaccine types.
Novavax did not present data in today’s meeting about the effects of mixing vaccine types.
The company is also testing its formula in adolescents and has submitted its existing data on vaccine safety and efficacy in people aged 12 to 18 to the FDA.
It's not yet clear when the Novavax vaccine will be made available in the U.S. The FDA and CDC must first finish reviewing manufacturing and safety data before the company may start distributing the vaccine.