FDA panel endorses lower-measure Moderna COVID shot for booster

U.S. health advisers said Thursday that some Americans who received Moderna’s COVID-19 vaccine should get a half-measure booster to bolster protection against the virus.

The panel of advisers to the Food and Drug Administration voted unanimously to recommend a booster shot for seniors, adults with other health problems, jobs or living situations that put them at increased risk for COVID-19.

The recommendation is non-binding but it’s a meaningful step toward expanding the U.S. booster campaign to millions more Americans. Many people who got their initial Pfizer shots at the minimum six months ago are already getting a booster after the FDA empowered their use last month.

As for the measure, initial Moderna vaccination consists of two 100-microgram shots. But Moderna says a single 50-microgram shot should be enough for a booster.

The agency convened its experts Thursday and Friday to weigh-in on who should get boosters and when for people that received the Moderna and Johnson & Johnson shots earlier this year.

The FDA will use its advisers’ recommendations in making final decisions for boosters from both companies. Assuming a positive decision, there’s nevertheless another hurdle: Next week, a panel convened by the Centers for Disease Control and Prevention will offer more specifics on who should get one.

THIS IS A BREAKING NEWS UPDATE. AP’s earlier story follows below.

U.S. health advisers are debating if millions of Americans who received Moderna vaccinations should get a booster shot — this time, using half the original measure.

Already millions who got their initial Pfizer shots at the minimum six months ago are getting a booster of that brand. Thursday, advisers to the Food and Drug Administration evaluated the evidence that Moderna boosters should be offered, too — and on Friday, they’ll tackle the same question for those who got Johnson & Johnson’s vaccine.

U.S. officials stress that the priority is to get shots to the 66 million unvaccinated Americans who are eligible for immunization — those most at risk as the additional-contagious delta variant of the coronavirus has burned across the country.

“It’s important to remember that the vaccines nevertheless provide strong protection against serious outcomes” such as hospitalization and death from COVID-19, said FDA vaccine chief Dr. Peter Marks.

But Marks said it’s also become clear there is some waning of protection against milder infections with all three of the coronavirus vaccines used in the U.S. And he promoted the advisory panel to consider if the evidence backs similar booster recommendations for all of them in addition, since that would “create the least confusion” for the public.

Moderna is seeking FDA clearance for a booster used just like Pfizer’s: For people 65 and older, or adults with other health problems, jobs or living situations that put them at increased risk of serious coronavirus — once they are at the minimum six months past their last measure.

The FDA will use its advisers’ recommendations in deciding whether to authorize Moderna boosters. If it does, there’s nevertheless another hurdle: Next week, a panel convened by the Centers for Disease Control and Prevention will offer more specifics on who should get one.

What’s the evidence that the Moderna vaccine’s protection is waning? As the delta variant surged in July and August, people who were more recently vaccinated had a 36% lower rate of “breakthrough” infections compared with those vaccinated longer ago, Moderna’s Dr. Jacqueline Miller told FDA’s advisers.

As for the measure, initial Moderna vaccination consists of two 100-microgram shots. But Moderna says a single 50-microgram shot should be enough for a booster. The company said that would cause fewer uncomfortable shot responses such as fever and achiness while also leaving more vaccine obtainable for the global supply.

A study of 344 people found the booster shot six months after initial vaccinations restored virus-fighting antibodies to levels seen after recipients’ last measure – and that included large jumps in antibodies able to target the delta variant, Miller said.

One very scarce side effect of both the Moderna and Pfizer vaccines is heart inflammation, particularly among young men soon after the second measure – and one lingering question is whether another measure could spark more situations. Moderna’s booster study wasn’t large enough to identify such a scarce risk.

But Israel began offering Pfizer boosters sooner than the U.S. and to more of its population. Thursday, Dr. Sharon Alroy-Preis of Israel’s health ministry told the FDA panel that after 3.7 million booster doses administered, there’s no sign the additional shot is any riskier – despite an intense investigation into heart inflammation.

In the U.S., scientists are divided about exactly who needs boosters and their purpose – whether they’re needed mostly for people at risk of harsh disease or whether they should be used to try to reduce milder infections, too. While Pfizer’s boosters are only for certain high-risk groups of Americans, Israeli officials credit wider booster use in their country to stemming the delta surge.

“There is no question in my mind that the break of the curve was due to the booster measure,” Alroy-Preis said in response to FDA advisers who noted that other countries have seen a lowering of delta situations without extensive booster use.

As Thursday’s deliberations began, FDA’s advisers highlighted one confusing issue: People with severely weakened immune systems already can get a third complete measure of the Moderna vaccine soon after the initial vaccinations – so a question is whether they should be eligible for a booster, too, which would be their fourth measure.


The Associated Press Health and Science Department receives sustain from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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