The Food and Drug Administration on Wednesday authorized Novavax’s protein-based Covid vaccine for adults, providing Americans with an alternative to the mRNA-based shots from Pfizer-BioNTech and Moderna.
The Novavax primary series is given in two doses, administered 21 days apart.
"Today’s authorization offers adults in the United States who have not yet received a Covid-19 vaccine another option that meets the FDA’s rigorous standards for safety, effectiveness and manufacturing quality needed to support emergency use authorization," FDA Commissioner Dr. Robert Califf said in a statement.
The FDA’s signoff isn’t the last step: The decision will now to go the Centers for Disease Control and Prevention and its advisory committee to issue their own recommendation on how the shots should be used. The CDC’s Advisory Committee on Immunization Practices is scheduled to meet on July 19.
The U.S. has secured 3.2 million doses of the vaccine, ready to be shipped to states once it receives the green light, the Biden administration announced Monday.
Wednesday's authorization comes more than a month after the agency’s vaccine advisory committee overwhelmingly recommended that the agency authorize the use of the shots and five months since the company first submitted its application to the FDA.
The shot has already been cleared for use in more than 40 countries, as well as the European Union, but manufacturing problems have hampered the company's efforts to be authorized in the U.S.
The FDA authorization took "longer than we wanted," Novavax CEO Stanley Erck told NBC News in an interview, "but we're there and we have gotten the company's first approval with the FDA for a vaccine in the United States."
Novavax’s vaccine uses an older technology found in other widely used vaccines, including the shots for hepatitis and shingles.
The vaccine uses synthetic coronavirus proteins to teach the body’s immune system to recognize bits of the virus.
Erck, as well as outside experts, say the Novavax shot is important to the nation’s vaccination campaign because it may persuade people who have been unable or unwilling to get the mRNA shots to finally get vaccinated. About 22% of people in the U.S. have not received a single dose of a Covid vaccine, according to data from the CDC.
"Some people are suspicious" of the mRNA vaccines, which use a new technology, said Dr. Ofer Levy, the director of the Precision Vaccines Program at Boston Children’s Hospital.
"There could be some people who were on the fence with the mRNA vaccines who would be willing to take this one," he said.
Clinical trial results, published in The New England Journal of Medicine in December, found two doses of Novavax’s vaccine were about 90% effective.
However, the clinical trials took place before the emergence of the extremely contagious omicron variant and its subvariants, which have been found to be more skilled at evading some of the immunity provided by other vaccines than previous strains.
The latest subvariants, called BA.4 and BA.5, are considered the most contagious forms of the virus to date. They made up about 70% of all new Covid cases in the U.S. for the week ending July 2, according to the CDC.
Erck said Novavax is confident its shot will provide strong protection against omicron and its family of subvariants.
The company released data in late December that found two doses of its vaccine triggered a strong immune response against the original omicron variant, though three doses appeared to be better. In addition, in late May, the company announced it began a clinical trial to test an updated vaccine designed to target the omicron variant.
Manufacturing for a modified vaccine that contains the BA.5 subvariant could begin later this summer, Erck said, with shots in arms beginning in November or December, pending authorization from regulators.
Novavax’s vaccine may be linked to a small but increased risk of myocarditis, according to an FDA briefing document. Pfizer's and Moderna's vaccines have been associated with the heart inflammation condition, particularly in young men, though the complication remains rare.
Novavax has said it will continuously monitor for all adverse events potentially related to the vaccine, including myocarditis.