After more than a year with two types of Covid-19 vaccines in use in the United States, another will be up for consideration by the US Food and Drug Administration next week.
The FDA’s vaccine advisers are set to meet Tuesday to consider Novavax’s coronavirus vaccine for the nation.
Based on data included in an agency briefing document posted Friday, an FDA review found that the vaccine’s efficacy was 90.4% overall against mild, moderate or severe Covid-19 for a period of 2½ months after completing the two-dose primary series. The document notes that, in a primary analysis, the vaccine efficacy fell to 78.6% among adults 65 and older.
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.
In an announcement published in December, the company reported that the vaccine had “broad cross-reactivity against Omicron and other circulating variants from a primary 2-dose regimen, with responses that increased following a third dose at six months.”
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.
In a statement Friday, Novavax addressed the heart inflammation concerns specifically: “We have learned that we can expect to see natural background events of myocarditis in any sufficiently large database, and that young males are at higher risk. Myocarditis is most often caused by nonspecific viral infections.” It said that the rate of myocarditis in vaccinated participants was similar to the placebo group.
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.
Novavax’s vaccine was developed as a protein subunit vaccine, a more traditional type of technology than the mRNA used for the Moderna and Pfizer vaccines. Other examples of subunit vaccines are the hepatitis B and pertussis vaccines.
“We believe our vaccine offers a differentiated option built on a well-understood protein-based vaccine platform that can be an alternative to the portfolio of available vaccines to help fight the Covid-19 pandemic,” Novavax CEO Stanley Erck said in a statement in January.
Novavax’s protein-based coronavirus vaccine relies on something called recombinant nanoparticle technology and Novavax’s adjuvant, called Matrix-M, to stimulate an immune response and high levels of neutralizing antibodies.
The four main types of Covid-19 vaccines in development
Even before coronavirus broke out in 2019, pharmaceutical companies were working on designs for vaccines they could quickly adapt to a pandemic strain of virus. Their work paid off in some of the new Covid-19 vaccines being tested and prepared for rollout as illustrated below.
Protein-based vaccines like Novavax’s work by getting the body’s immune system to recognize little modified pieces of the virus it’s targeting. In Novavax’s case, that means pieces of the coronavirus spike protein.
When the genetic sequence for the virus that causes Covid-19 was published, scientists around the world quickly identified it as a coronavirus because of the “spike proteins” on its surface. These spikes form large protrusions, giving coronaviruses the appearance of wearing crowns, and “corona” is the Latin word for “crown.”