A panel of top US scientists has recommended approving Moderna’s application to provide third shots of its Covid-19 vaccine, lending some momentum to the US’s booster rollout.
Advisers to the US Food and Drug Administration voted on Thursday in favour of allowing 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 FDA will make a final decision in the coming days on whether to give the go-ahead for people to receive third shots of the vaccine. If so it will accelerate the Biden administration’s plans for a widespread booster programme, which President Joe Biden has said will help bring down the country’s high number of Covid-19 cases.
The vote comes during a two-day meeting in which the FDA panel 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.
Scientists on the FDA committee expressed concerns about aspects of Moderna’s application, including whether there was enough evidence on how quickly protection from the initial two doses wanes, and what the impact would be of using a half-dose for the booster shot.
They ultimately voted unanimously to approve the application in part because they had already done so for Pfizer.
Stanley Perlman, professor of microbiology and immunology at the University of Iowa, 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.”
Patrick Moore, a professor at the University of Pittsburgh Cancer Institute, said: “The data itself is not strong, but it is certainly going in a direction that is supportive of this vote.”
Biden in August announced that every American adult would be offered a booster shot eight months after their initial vaccination was complete. But those plans hit a hurdle last month when the FDA’s advisory committee rejected Pfizer’s application to provide all vaccinated Americans with extra doses, and chose instead to narrow the eligibility criteria only to older people or those at risk of severe Covid-19.
Biden on Thursday said that more than a third of people over 65 had got a booster shot since the Pfizer authorisation. “We are going to continue to provide that additional protection to seniors and others as we as we head into the holidays,” he said.
Members of the committee were told of mounting evidence that the effectiveness of two-dose vaccines begins to wane after a few months.
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 significantly more likely to become infected than those who received their second dose later in the year, the company said.
Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, 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.”
Marks also tried to address members’ concerns about the small sample sizes in the studies into the effectiveness of booster doses, saying the studies “do all trend in the same direction”.
The FDA also showed members data indicating that a third shot did not cause stronger side effects than a second dose.
After the FDA gives its final decision, it will be up to the US Centers for Disease Control and Prevention to issue its own recommendations for who should receive the boosters.