Ahead of a two-day meeting that could clear the way to offer booster shots to millions more Americans, scientists from the Food and Drug Administration carefully presented the data available from Moderna and Johnson & Johnson, but did not arrive. to vigorously advocate for the authorization of an additional dose of the vaccine from either company.
In separate briefing documents, which are intended to lay out the FDA’s position before outside advisers meet Thursday and Friday, agency staff appeared to have a cautious opinion on whether booster doses are now needed.
Overall, “the data indicates that currently licensed or licensed COVID-19 vaccines in the US still provide protection against severe COVID-19 illness and death in the United States,” the FDA scientists wrote in your review of Moderna’s request for approval of a third dose.
They said the same in their review of J & J’s application, although they noted that the efficacy of the company’s single-shot vaccine was less than that of Moderna and Pfizer’s two-shot messenger RNA regimens.
However, agency staff were equally neutral in their review of Pfizer’s application last month, and the FDA ultimately authorized booster doses of that vaccine for many of the most vulnerable Americans.
Moderna had originally asked the FDA to authorize a booster dose of its vaccine for people 12 years of age and older. But the company amended its request to match what The FDA cleared the Pfizer injection on September 22.. That clearance, granted after back-and-forth meetings of advisers from both the FDA and the Centers for Disease Control and Prevention, included adults 65 and older, younger adults with underlying medical conditions, and people 18 and older. years whose “frequent institutional or occupational exposure”. puts them at greater risk.
Importantly, Moderna proposes using a third dose that is half the size of the first two. J&J, by comparison, is asking the FDA to approve a second dose that is the same as the first.
Advisers are likely to spend time Thursday and Friday discussing the security of the reinforcements. During their meeting on the authorization of the Pfizer booster, committee members focused on the risk of myocarditis, an inflammation of the heart that has been associated in rare cases with the mRNA vaccine, particularly in younger men. (COVID-19 can also cause myocarditis.)
That discussion is likely to be repeated, as a similar pattern has been seen with Moderna’s and Pfizer’s vaccines.
“No information is yet available on possible long-term sequelae and outcomes in affected individuals, or whether the vaccine could be associated with initially subclinical myocarditis,” the agency noted in the briefing.
Much of Moderna’s case for a booster shot, to be given six months after the second dose, is based largely on data showing antibody levels declining over time, as well as the increased threat. of the delta variant.
J&J also relies on antibody data, as well as the results of a late-stage clinical trial that tested two doses of its vaccine two months apart. Meanwhile, two immunogenicity studies looked at doses spaced two to three months after the first or six months after. The results of both showed an increase in antibody levels, although the increase was greater with the interval of six months.
Some of that data appears to have taken into account J & J’s request for a more flexible timing of a possible booster dose between two and six months after the first in people over 18 years of age.
FDA staff indicated that the agency intends to seek the advice of its advisers on the ideal timing of a second dose of J&J.
However, a more important question facing the regulator is whether the combination of booster shots could better protect people after their primary vaccination with another vaccine. That debate could be particularly relevant for the J&J vaccine, which the FDA says has an efficacy that is “consistently lower than the highest effectiveness estimates for COVID-19 mRNA vaccines.”
The committee will hear from the National Institutes of Health about a study examining the so-called heterologous push strategy. However, that presentation will take place on Friday, after the committee has been asked to vote on its recommendations for both vaccines.