(CNN) — After more than a year with two types of COVID-19 vaccines in use in the United States, another one will be considered by the US Food and Drug Administration.
The FDA’s vaccine advisers will meet on Tuesday to consider Novavax’s coronavirus vaccine for the nation.
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Based on data included in an agency briefing paper posted Friday, an FDA review found the vaccine’s efficacy totaled 90.4% against mild, moderate, or severe COVID-19 over a period of 2½ months after completion of the primary two-dose series. The paper notes that, in a primary analysis, vaccine efficacy decreased to 78.6% in adults age 65 and older.
Those efficacy figures were collected before the emergence of the Omicron coronavirus variant. It remains unclear how long the protection will last 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 2-dose primary regimen, with responses increasing after a third dose at six months.”
Novavax’s vaccine, called NVX-CoV2373, is given as two doses three weeks apart for the primary vaccination course.
While most side effects of the vaccine were mild to moderate and lasted only a few days, the FDA described rare cases of myocarditis and pericarditis — inflammation of the heart muscle and inflammation of tissue around the heart — associated with the vaccine.
Multiple cases of myocarditis/pericarditis were reported in temporal relationship to administration of NVX-CoV2373, similar to myocarditis following mRNA COVID-19 vaccines and raising concerns about a causal relationship to NVX-CoV2373, says FDA briefing paper .
The document describes six cases that occurred after vaccination with Novavax. Five were among men 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 in people who received the Pfizer/BioNTech and Moderna COVID-19 mRNA vaccines now in use in the United States.
In a statement Friday, Novavax specifically addressed concerns about heart inflammation: “We have learned that we can expect natural background events of myocarditis in any large enough database, and that young men are at higher risk. Myocarditis is usually caused by non-specific viral infections. infections.” It said the rate of myocarditis in vaccinated participants was similar to the placebo group: 0.007% and 0.005%, respectively.
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 side effects of the vaccine were injection site pain, fatigue, headache, and muscle aches. Reactions were reported more frequently in younger participants in the clinical trials of the vaccine.
In its briefing paper, the FDA summarized: “The known benefits in vaccine recipients 18 years and older over placebo are reduction in the risk of mild to severe COVID-19 occurring at least 7 days after the second primary vaccination course.”
At Tuesday’s meeting, members of the FDA’s Vaccine Advisory Committee will vote on the question: “Do the benefits of the Novavax COVID-19 vaccine when given as a series of 2 doses outweigh the risks for use? in individuals? 18 years and older?”
‘We believe our vaccine offers a differentiated option’
In late January, Novavax announced it had filed a request with the FDA to approve its coronavirus vaccine for emergency use in the United States.
In November, Indonesia became the first country to authorize the emergency use of Novavax’s vaccine. Since then, it has been authorized in the European Union, the United Kingdom, Canada, South Korea, Australia, India, the Philippines and New Zealand, among others.
While most adults in the United States have been vaccinated against COVID-19, the company chief has said it sees Novavax’s vaccine as a possible booster dose option, regardless of which type of vaccine was given for a person’s initial doses.
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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 whooping cough vaccines.
“We believe our vaccine offers a differentiated option, built on a well-understood protein-based vaccine platform that can provide an alternative to the portfolio of available vaccines to help fight the COVID-19 pandemic,” said Novavax CEO Stanley Erck in a statement. statement in January.
Novavax’s protein-based coronavirus vaccine is based on something called recombinant nanoparticle technology and Novavax’s adjuvant called Matrix-M to stimulate an immune response and high levels of neutralizing antibodies.
Protein-based vaccines, like Novavax’s work, allow the body’s immune system to recognize small modified pieces of the virus it targets. 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 spines form large projections, giving coronaviruses the appearance of crowns, and “corona” is the Latin word for “crown.”
Novavax scientists identified the gene for the spike protein and created a modified version of that gene. The researchers clone the genes into a baculovirus that infects insects. They then infected moth cells — particularly autumn armyworm cells — prompting them to produce the coronavirus spike protein.
These virus-like nanoparticles were collected to make Novavax’s vaccine.
“The whole idea of the vaccine is to show the immune system something that looks, tastes and acts like a virus, except it doesn’t make you sick. So we made the spike protein. We put it in a particle — basically like a bubble — and it’s the size of the virus,” said Dr. Gregory Glenn, president of research and development for Novavax, told CNN last year.
“It’s not contagious. We never get to the coronavirus itself,” Glenn added. “Then that’s given to people, and they make an immune response that’s very much focused on the peak — and I’d say the hallmark of our vaccine is that it’s a very strong immune response with very few side effects, and the dose is very small and the vaccine can be stored at normal refrigerated temperatures.”
Novavax starts Phase 3 study of Omicron-specific booster
As Novavax is seeking authorization for the emergency use of its NVX-CoV2373 vaccine, it is also studying a separate vaccine specifically targeting the Omicron variant called NVX-CoV2515. The company announced this week that it has started a phase 3 study of this vaccine, assessing its safety and efficacy as a booster injection.
“The trial will also seek to determine antibody responses to a bivalent vaccine, containing both NVX-CoV2373 and NVX-CoV2515, administered to participants who received a booster series of an mRNA vaccine,” Novavax said in a press release.
The trial will analyze the Omicron-specific vaccine and a bivalent vaccine in more than 1,000 participants in Australia.
Two doses of the Omicron-specific vaccine or the original NVX-CoV2373 vaccine will be given after three doses of either the Pfizer-BioNTech and/or Moderna vaccines received at least three months before the participants entered the trial .
Similarly, two doses of the Omicron-specific vaccine or the original NVX-CoV2373 will be given after two doses of both mRNA vaccines received at least six months prior to trial entry.
Two doses of the bivalent vaccine will be administered to participants who have been vaccinated with three doses of either mRNA vaccine at least three months prior to entering the trial.
The trial will last approximately 10 months and first results are expected in the second half of this year.
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