FDA panel green-lights Moderna COVID boosters for risk groups

COVID vaccine vial and syringe
Filling syringe from COVID vaccine vial

Gov Tom Wolf / Flickr cc

Vaccine advisors for the Food and Drug Administration (FDA) today unanimously approved a third and smaller dose of Moderna's COVID-19 vaccine for vulnerable groups.

Today's meeting of the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) was the first of two days of booster-dose deliberations, which tomorrow will cover the Johnson & Johnson vaccine and mix-and-match strategies.

In advance of tomorrow's VRBPAC meetings, a research team based at the National Institutes of Health (NIH) yesterday released a preprint study suggesting that all vaccine combinations were well tolerated and immunogenic, but Johnson & Johnson recipients got a bigger immune response from an mRNA vaccine booster than a second dose of their original vaccine.

Approval aligns with Pfizer risk groups

In their vote, the 19-member group said the available data support the safety and efficacy of a booster dose of the Moderna vaccine, under emergency use authorization (EUA), in the same groups as for the Pfizer-BioNTech booster: those ages 65 and older, those ages 18 to 64 who are at risk of severe COVID-19, and those ages 18 to 64 whose frequent exposure in institutional or occupational settings put them at high risk for serious COVID-19 complications.

The decision is nonbinding, and FDA officials will make the final decision before handing the recommendation discussion off to the Centers for Disease Control and Prevention (CDC) vaccine advisory group, which will meet next week to weigh the latest booster developments.

In their Moderna booster discussions, the group had to navigate a more complicated course than they did last month for the Pfizer-BioNTech boosters. Earlier this week, Moderna announced that its request for booster-dose authorization was for a half-strength version for people ages 18 and older—50 micrograms rather than 100 micrograms. It said the half dose would raise antibody levels while minimizing side effects and would allow the company to beef up the global supply of the vaccine.

Separately, the federal officials had advised in August that those with moderate or severe immune compromise receive a third dose of an mRNA vaccine at least 28 days after the initial two doses. Health workers will need to consider two different dosages when offering additional doses of the Moderna vaccine.

In a FDA briefing document released on Oct 12 ahead of the VRBPAC meeting, the agency's scientists said data on the Moderna vaccine revealed a mixed picture on the need for boosters, with some recent effectiveness studies showing declining efficacy over time against symptomatic infection or against the Delta (B1617.2) variant, and others showing no drop-off. They concluded that all COVID-19 vaccines that are authorized in the United States protect against severe disease and death.

J & J, mixed doses on deck for tomorrow

Tomorrow VRBPAC will discuss and vote on Johnson & Johnson boosters. Earlier this month, the company applied to amend its emergency use authorization (EUA) for its one-dose vaccine in those 18 and older to include a booster dose. It presented data that suggest a booster increases effectiveness to 94%. Currently, the one-dose vaccine is 71% protective, according to the CDC.

Afterward, the group is also slated to discuss mix-and-match doses, but it's not clear if they will vote on the issue.

Regarding the NIH preprint study, which hasn't been peer reviewed, researchers found that those who received the Johnson & Johnson shot had stronger antibody levels after they got an mRNA vaccine booster, rather than a Johnson & Johnson booster. The study included 458 people who received a different vaccine 12 weeks after their initial shot, examining 9 different vaccine combinations. The Moderna vaccine was assessed at the full 100-microgram dose.

Also, those who received either Moderna or Pfizer initially and received a booster of the other company's mRNA vaccine had similarly robust immune responses.

Leana Wen, MD, former Baltimore health commissioner and contributing columnist for the Washington Post, said yesterday on Twitter that the key finding for Johnson & Johnson recipients was that neutralizing antibodies rose 4 times after the Johnson & Johnson booster, 35 times after a booster of the Pfizer vaccine, and 76 times after a Moderna booster shot.

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