Those efficacy numbers were collected before the emergence of the Omicron coronavirus variant. It remains unclear how long protection lasts or how well the vaccine will protect against Omicron.
Novavax’s vaccine, called NVX-CoV2373, is given as two doses three weeks apart for the primary vaccination series.
Although most adverse reactions to the vaccine were mild to moderate and lasted just a few days, the FDA did describe rare events of myocarditis and pericarditis — inflammation of the heart muscle and inflammation of tissue surrounding the heart — associated with the vaccine.
“Multiple events of myocarditis/ pericarditis were reported in temporal relationship to NVX-CoV2373 administration, similar to myocarditis following mRNA COVID-19 vaccines and raising concern for a causal relationship to NVX-CoV2373,” the FDA’s briefing document says.
The document describes six cases that happened after vaccination with Novavax. Five were among males ranging in age from 16 to 67. Of the six cases, five were hospitalized but have since recovered.
An increased risk of myocarditis and pericarditis has been identified among people who received the mRNA Pfizer/BioNTech and Moderna Covid-19 vaccines now used in the United States.
The company added, “we believe there is insufficient evidence to establish a causal relationship. We will continue to monitor all adverse events, including myocarditis and pericarditis.”
The most common adverse reactions to the vaccine were pain at the injection site, fatigue, headache and muscle ache. Reactions were reported more commonly in younger participants in the vaccine’s clinical trials.
In its briefing document, the FDA summarized, “The known benefits among vaccine recipients 18 years of age and older relative to placebo are reduction in the risk of mild to severe COVID-19 occurring at least 7 days after the second primary series vaccination.”
In Tuesday’s meeting, the FDA’s vaccine advisory committee members will vote on the question: “Based on the totality of scientific evidence available, do the benefits of the Novavax COVID-19 Vaccine when administered as a 2-dose series outweigh its risks for use in individuals 18 years of age and older?”
‘We believe our vaccine offers a differentiated option’
In late January, Novavax announced that it had submitted a request for the FDA to authorize its coronavirus vaccine for emergency use in the United States.
In November, Indonesia became the first country to grant emergency use authorization of Novavax’s vaccine. It has since been authorized in the European Union, the United Kingdom, Canada, South Korea, Australia, India, the Philippines and New Zealand, among other countries.
Even though most adults in the United States have been vaccinated against Covid-19, the head of the company has said that it sees Novavax’s vaccine as a potential option for booster doses, regardless of which type of vaccine was given for a person’s initial doses.
Read More: FDA advisers to weigh risks and benefits of Novavax’s Covid-19 vaccine