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FDA advisers vote in favor of authorizing Novavax Covid vaccine

If authorized, the Novavax shot would be the only protein-based Covid vaccine available in the U.S., which might appeal to some holdouts, some experts say.

An independent advisory group to the Food and Drug Administration voted Tuesday in favor of authorizing the Covid vaccine made by drugmaker Novavax for adults ages 18 and older.

Twenty-one members of the committee voted yes, and none voted no; one person abstained. Next, the FDA will decide whether to authorize the shot for emergency use, which would make it the fourth coronavirus vaccine available in the U.S. The FDA often follows the group’s recommendations.

If it is authorized, Novavax's shot would be the only protein-based Covid vaccine distributed in the country. That formulation is more traditional than the ones used in the mRNA shots from Pfizer and Moderna. The FDA has approved several protein-based vaccines in the past, including one for hepatitis B and another for shingles.

Because of that, some of the FDA committee members think it might appeal to U.S. residents who have thus far chosen not to get vaccinated.

“Having a protein-based alternative may be more comfortable for some in terms of their acceptance of vaccines,” Dr. Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, said at the meeting.

One-third of people in the U.S. are not fully vaccinated for Covid, and 22 percent have not received a single Covid vaccine dose, according to the Centers for Disease Control and Prevention.

Novavax's vaccine appeared highly effective in its trial: It lowered the risk of symptomatic Covid by 90 percent in a group of more than 30,000 people in the U.S. and Mexico. But because the trial was conducted from December 2020 to February 2021, when the alpha variant of the coronavirus was dominant, it did not determine the vaccine’s efficacy against the virus’s omicron variant.

“It is quite disappointing that we don’t have any data in the omicron era,” said a committee member, Dr. Mark Sawyer, an infectious disease specialist at Rady Children’s Hospital in San Diego. But he added that the data “is quite similar to what we’ve approved in the past with other vaccines.”

The Novavax option

The World Health Organization authorized the Novavax vaccine for emergency use in December. It has also been authorized in Australia, the European Union, India, Indonesia, the Philippines, South Korea and the United Kingdom. Novavax said Tuesday that 744,000 doses had been administered worldwide as of April.

One advantage of the vaccine is that it can be stored in a regular refrigerator for up to six months, whereas mRNA vaccines must be kept at subzero temperatures, making them harder to transport.

Marks said in Tuesday’s meeting that although the U.S. has had other vaccine options for a while, "anything we can do to get people more comfortable to be able to accept these potentially lifesaving medical products is something that we feel we are compelled to do."

But some other experts questioned whether vaccine-hesitant people will think of Novavax any differently. The U.S. already discarded 82.1 million Covid vaccine doses from December 2020 through mid-May — more than 11 percent of the doses distributed by the federal government, according to CDC data.

“I’m a little skeptical about how many of the vaccine hesitant are just waiting for this vaccine and they’re going to be convinced that this is better for them than the vaccines that are currently available,” said a committee member, Dr. Arthur Reingold, the division head of epidemiology and biostatistics at the University of California, Berkeley, School of Public Health.

Novavax's manufacturing hurdles caused delays

Novavax’s vaccine consists of two doses, given three weeks apart. It uses the purified spike protein from the coronavirus, along with an immune-boosting ingredient called an adjuvant, to stimulate the production of antibodies. By contrast, mRNA vaccines use a snippet of the coronavirus’s genome to instruct the body to produce the spike protein internally, which then prompts the development of antibodies.

Johnson & Johnson’s Covid vaccine, meanwhile, introduces a gene for the spike protein into the body via a genetically engineered common cold virus. But because of the risk of blood clots, that shot is being offered only to adults who refuse the other Covid vaccines or cannot receive them for medical reasons.

Novavax has had its trial data for adults since last June, but it ran into manufacturing issues that led to delays in its application for U.S. authorization. Politico reported in October that Novavax could not consistently verify the quality of its vaccine batches. The company said in a statement soon after that it was committed to "stringent standards of production and manufacturing." Novavax filed for authorization in January.

Dr. Goutam Sen, the review committee chair of the FDA’s Vaccines and Related Product Applications division, said Tuesday that Novavax’s manufacturing process has changed over time and that the company has kept the FDA updated about it. But that also means the vaccine product used in the trials is not quite the same as the one that would be distributed if it is authorized.

Experts raised questions about myocarditis

The Novavax trial identified five instances of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the membrane surrounding the heart) within two weeks of vaccination, "raising concern for a causal relationship," according to an FDA briefing document.

By comparison, the CDC identified 1,226 reports of myocarditis out of 296 million Pfizer and Moderna vaccinations from December 2020 to June 2021. But some committee experts said it might not be fair to compare myocarditis risk across vaccine platforms yet, because Novavax has not been distributed as widely.

"It would be, at this stage, difficult to say it occurs more frequently with one vaccine platform than another," said Dr. Cody Meissner, the chief of the pediatrics infectious disease division at Tufts University School of Medicine.

The CDC identified around 5,000 cases of myocarditis among 1.45 million people diagnosed with Covid from March 2020 to February 2021 — a much higher rate than has been observed in connection to any other Covid vaccine so far.