US FDA backs half-dose Moderna booster for at-risk adults

Washington: A panel of advisors to the US Food and Drug Administration have voted unanimously recommending Moderna's Covid booster shot for people at risk.

The FDA's Vaccines and Related Biological Products Advisory Committee met on Thursday to discuss data on the safety and effectiveness of Moderna booster shots in adults.

It allowed Moderna to supply third doses of its vaccine to people who had their second doses at least six months ago and are over 65, have underlying health conditions, or whose jobs put them at high risk of contracting severe Covid-19. All 19 voting members voted in favour, the Financial Times reported.

Earlier this month, the US regulators had authorised Covid booster shots of Pfizer and BioNTech's. However, unlike for Pfizer, Moderna has been recommended for only half-dose booster to bolster protection against the virus.

The initial Moderna vaccination consists of two 100-microgram shots, but Moderna has said that a single 50-microgram shot should be enough for a booster.

The FDA's final decision will be handed to the US Centers for Disease Control and Prevention (CDC) and its vaccine advisory committee, which will then make their own decision. The CDC's next vaccine advisory meeting is scheduled for October 20-21 where it is expected to discuss the boosters.

The FDA panel's two-day meeting will also consider whether to recommend a booster of Johnson & Johnson's one-dose vaccine. They will also discuss the results of a preliminary study of a US trial on mixing Covid-19 vaccines as part of a booster programme -- a practice that some experts believe could boost a person's immune response and ease logistical challenges in rolling out boosters, the report said.

"I support this (application) because we've already approved it for Pfizer and I don't see how we can possibly not approve it for Moderna and not have most US folks be completely confused," Stanley Perlman, professor of microbiology and immunology at the University of Iowa, was quoted as saying.

Moderna presented data showing a sudden rise in the proportion of vaccinated people getting Covid-19 in July and August, seven months after the vaccine rollout began, which it said pointed to the need for boosters.

Those vaccinated earlier were more likely to become infected than those who received their second dose later in the year, the company said.

There seems to be some waning in protection against overall Covid-19 infections. We need to account for the fact that mild and moderate Covid-19 can be associated with adverse outcomes," Peter Marks, the director of the FDA's Center for Biologics Evaluation and Research was quoted as saying.

Just under 188 million people in the US have now been fully vaccinated, according to the CDC. Around 9 million of those have also received booster doses, data shows. More people are now getting booster doses than receiving their first shots, it added.