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A key FDA panel voted 19 to 0 in favor of the emergency use authorization (EUA) for the Moderna-NIAID COVID-19 vaccine for older and high-risk adults. Jon Cherry/Getty Images
  • A group of experts voted to recommend a booster of the Moderna-NIAID COVID-19 vaccine for older adults and others at higher risk.
  • The recommendations are similar to the booster program for the Pfizer-BioNTech.
  • Adults 65 and over, adults 18-64 at high risk of severe COVID-19, and adults 18-64 who work in high-exposure occupations would all be eligible for the Moderna booster.
  • The extra shot is recommended after 6 months from the original second dose.
  • The booster formulation will be half the volume of the original sequence, 50 micrograms versus 100 micrograms.

An advisory panel to the Food and Drug Administration (FDA) voted unanimously on Oct. 14 to recommend that the agency authorize a booster dose of the Moderna-NIAID COVID-19 vaccine for some U.S. adults at high risk.

The recommendation mirrors the emergency use authorization (EUA) of the Pfizer-BioNTech booster, and includes the following groups:

  • People 65 years and older
  • People 18 to 64 years of age who are at high risk of severe COVID-19
  • People 18 to 64 years of age who are at high risk of serious COVID-19 complications due to frequent job-related or institutional exposure to the coronavirus

The booster could be given at least 6 months after the second dose.

In addition, the booster would be half the dosage used for the first and second doses — 50 micrograms versus 100 micrograms.

The Vaccines and Related Biological Products Advisory Committee (VRBPAC) was 19 to 0 in favor of the emergency use authorization (EUA).

The FDA will decide whether to accept the advisory committee’s recommendation.

After that, the Centers for Disease Control and Prevention’s vaccine advisory committee will meet to decide on which groups should receive the Moderna-NIAID booster.

Data presented during the Oct. 14 meeting show that COVID-19 vaccines currently approved in the United States continue to protect against severe illness and death due to the coronavirus.

However, “some real-world effectiveness studies have suggested declining efficacy of Moderna COVID-19 vaccine over time against symptomatic infection or against the delta variant, while others have not,” the FDA scientists said in a briefing document.

The Pfizer-BioNTech and Johnson & Johnson vaccines have also shown some decrease in effectiveness against infection in the months following complete vaccination.

In addition, the panel heard an update from Israeli researchers about that country’s booster campaign, which has mainly involved the Pfizer-BioNTech vaccine.

Data from Israel show a drop in COVID-19 cases and severe disease after the rollout of the boosters. The effects were most pronounced for people over age 60 but also occurred with younger people.

As more age groups became eligible for a booster, the country saw a drop in overall cases, including among unvaccinated.

“The administration of the booster dose helped Israel dampen the infections and the severe cases in the fourth wave,” Dr. Sharon Alroy-Preis, director of public health services at the Ministry of Health, Israel, told the committee members.

During the meeting, some members also spoke about the potential of boosters to reduce the long-term health effects of infections in fully vaccinated people.

“We now know from recently published studies that vaccinated individuals can develop long COVID-19 if they experience breakthrough COVID-19 infection of any severity,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said during the meeting.

Moderna’s phase 2 booster trial was too small to show whether a booster dose reduces the risk of infection or severe COVID-19.

Instead, scientists measured neutralizing antibodies in the blood after the booster and compared them to levels after the second dose.

In the trial, 171 fully vaccinated adults received a booster 6 months after their second dose. The booster was 50 micrograms, half the dose of the first and second doses.

Of these people, 88 percent saw at least a four-fold rise in their level of neutralizing antibodies, a sign of how well the vaccine protects against infection and disease.

People who started with lower antibody levels were more likely to see an increase this large.

However, the difference in the immune response between the booster and the primary was not significant enough to meet the company’s definition of success.

Some members of the committee expressed concern about the data submitted by Moderna.

The data themselves are not strong, but they are “certainly going in a direction” that is supportive of this EUA, committee member Dr. Patrick Moore, a professor at the University of Pittsburgh Cancer Institute, said during the meeting.

The phase 2 trial also showed that the side effects of the booster dose were similar to those after the primary series. The most common ones were headaches and fatigue.

Specific side effects were more common after the booster dose.

People under 65 were more likely to have swollen lymph nodes in the armpit after the booster than after the second dose. This was primarily mild and short-lived.

Muscle and joint pain were also more common in people 65 and older after the booster than the second dose.

However, the rates of these side effects were similar to the rates seen in the company’s larger phase 3 trial.

One side effect that will require ongoing monitoring is heart inflammation — myocarditis and pericarditis.

This is a known side effect of the mRNA vaccines. Previous data show that these conditions are more common after the second dose and in younger males. Most cases are mild and respond well to treatment.

Moderna’s phase 2 booster trial was not large enough to show the rate of myocarditis after the booster.

The FDA and the Centers for Disease Control and Prevention (CDC) will continue to monitor people who receive boosters for myocarditis and other adverse effects.

Preliminary data presented during the meeting by the Israeli researchers suggest that the rate of myocarditis after the booster is not higher than after the second dose.

“I’m very confident about the serious events,” said Alroy-Preis.

However, Israeli researchers have only longer-term follow-up data on about half of the younger people who have received the booster. This is the group that is at greater risk of heart inflammation.