F.D.A. Advisers Consider the Next Generation of Covid Vaccines

An independent panel of advisers to the Food and Drug Administration will meet on Tuesday to consider options for updating the coronavirus vaccines for a booster campaign aimed at warding off fall or winter surges.

The experts will vote at the end of the daylong meeting on whether the vaccines should be reformulated to target either Omicron or one of its subvariants, and if so, which one. You can watch the meeting live on YouTube here, which is scheduled to begin at 8:30 a.m. Eastern.

Discussion questions circulated by the F.D.A. show that the advisory group will also be asked whether vaccines that combine the original formulation with one targeting Omicron would be preferable to vaccines that only target Omicron. Data supporting the option that combines the so-called “prototype,” or existing, vaccines with Omicron has received mixed reviews so far, with regulators suggesting in briefing materials for Tuesday’s meeting that such a design is “already somewhat outdated.”

Regulators are also planning to ask the advisers whether health providers should continue using the original vaccine formulation this fall on people who have not yet been fully vaccinated if the makeup of the booster shot changes.

Omicron subvariants known as BA.4 and BA.5 now make up more than a third of cases in the country, a possible hint of what could be circulating later this year. A vaccine that protects against those versions of the virus may be of the most interest to the F.D.A. panel and the federal scientists who will determine what to target.

Members of the F.D.A. committee may be divided on who should receive new vaccines. Some might say that a fall booster will be broadly necessary, while others might argue that because the current vaccines’ protection against severe forms of Covid-19 has held, the next round of shots should be limited to high-risk individuals, at least to start. Dr. Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia and a member of the committee, has said that only people over 70, and those over 50 with serious underlying conditions, will likely need a fall booster shot.

The possibility of a more advanced vaccine has been teased for months by federal health officials, who have warned that as the virus evolves rapidly, vaccine-induced protection against infection has faded, allowing some Americans to be reinfected even in the span of several months.

In the briefing materials published ahead of Tuesday’s meeting, F.D.A. officials said the risk of another major Covid outbreak will rise later this year “due to the combination of waning immunity, further evolution of variants, and increased indoor activity.”

The World Health Organization said this month that updated versions of the vaccines should be studied because their protection against symptomatic illness has deteriorated so quickly.

Moderna and Pfizer, the makers of the two most widely-used vaccines in the United States, have both studied Omicron-specific vaccines, expecting them to be seriously considered as the fall booster option. But the research has been complicated by the subvariants, for which neither company has developed shots yet.

If the government decides it wants a booster shot that targets BA.4 and BA.5, the vaccine manufacturers will have to race to produce the doses by fall. Pfizer may be able to meet an October deadline, according to people familiar with the company’s operations, while Moderna has said it likely would not have the option ready until late this year or early next year.

The discussion on Tuesday will likely serve as a referendum of sorts on the future of the pandemic in the United States and whether the fast-changing virus could lead to a significant spike in hospitalizations later this year. Justin T. Lessler, an epidemiologist at the University of North Carolina, Chapel Hill, is set to present modeling to the committee on the trajectory of the virus.

Deaths have remained below 400 a day in recent weeks even as Omicron cases surged this spring, with people dying from Covid at a rate close to the lowest of the pandemic. Infectious disease experts have attributed the trend to the protection Americans have gained from vaccination and infection, and from new treatments, such as the oral antiviral pill Paxlovid.