Covid-19 Vaccines and Variant News: Live Updates

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

The experts will vote on whether the vaccines should be reformulated to target Omicron or its subvariants, even though the virus might evolve yet again by the fall. You can watch the meeting live on YouTube here.

Dr. Peter Marks, who oversees the F.D.A.’s vaccines office, said at the beginning of Tuesday’s meeting that a good match between a vaccine and a variant could lead to greater vaccine effectiveness and durability. He said the Omicron subvariants known as BA.4 and BA.5 were “poised to become the dominant variant,” a hint of where regulators may look in choosing a new composition for shots.

Not long after his remarks, the Centers for Disease Control and Prevention released new estimates showing the two subvariants now make up more than half of new cases in the country.

Dr. Marks displayed a timeline suggesting that regulators would decide on a new vaccine’s makeup by early July, and that a fall booster campaign with a newly designed shot could begin in October. Manufacturers of the mRNA vaccines, made by Moderna and Pfizer-BioNTech, require roughly three months to begin producing doses with a new composition.

Clinical trial results on a combination of the so-called “prototype,” or existing, vaccines and Omicron itself have received mixed reviews so far. In briefing materials, regulators suggested that such a design is “already somewhat outdated.”

The panel is also considering whether health providers should continue using the original vaccine formulation this fall for people who have not yet been fully vaccinated if the makeup of the booster changes. Dr. Kanta Subbarao, an adviser to the World Health Organization, said the original shots continue to protect against severe disease, but a new booster dose targeting some component of Omicron could increase the breadth of immunity.

There was little talk about any variant other than Omicron, which has proved to be a game-changer in the pandemic. Dr. Jerry Weir, an F.D.A. official, said that Omicron or its subvariants have dominated for about six months now and may well continue to prevail. Overall, he said, the data indicate that a booster that incorporates an Omicron component produces a better antibody response against that family of the virus and offers “the potential for improved vaccine effectiveness.”

Members of the panel may be divided on who should receive new vaccines. Some have suggested that a fall booster will be broadly necessary, while others contend that because the current vaccines’ protection has held up against severe disease, the next round of shots should be limited to high-risk individuals, at least to start.

Although the overall death rate is low now compared to earlier in the pandemic, C.D.C. officials said Americans 70 and older have driven increases in hospitalizations. Heather Scobie, an agency epidemiologist, said that despite “rather poor” uptake, second boosters were reducing the risk of death in older adults While figuring out the next step in the vaccination campaign, she said, public health officials should “be pushing the second boosters in older ages to protect against serious illness.”

Federal health officials have suggested for months that more advanced vaccines may be needed to combat the rapidly evolving virus, warning that vaccine-induced protection against infection has faded, allowing some Americans to be reinfected even in the span of several months.

In briefing materials, F.D.A. officials said the risk of another major outbreak will rise later this year “due to the combination of waning immunity, further evolution of variants, and increased indoor activity.” Justin T. Lessler, an epidemiologist with the University of North Carolina at Chapel Hill, presented a series of projections on the U.S. trajectory of the virus.

Under the most optimistic scenario, his team anticipated 95,000 deaths between in the 12-month period ending March 2023. Under the most pessimistic, the nation would see over 200,000 deaths. He said his team’s more pessimistic scenarios, which tried to factor in waning immunity and new variants, have been more accurate so far.

Still, he cautioned that the unpredictable nature of the pandemic made it difficult to make assumptions about new variants and the havoc they could cause.

“That’s the problem, because we’re being asked, more or less, to have a crystal ball today,” said Dr. Arnold S. Monto, a University of Michigan epidemiologist and the F.D.A. committee’s chair.

Moderna and Pfizer, the makers of the two most widely-used vaccines in the United States, have both studied vaccines that target the first version of Omicron, 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 F.D.A. chooses a vaccine that targets BA.4 or BA.5, it is unclear whether either company will be able to study it and manufacture doses in time for a fall booster campaign.

Pfizer presented the only data on such a formulation — preliminary data from a mouse trial — suggesting it worked better against all Omicron’s subvariants than the existing vaccine does. But a company official said researchers do not yet have a side-by-side comparison with a version targeting Omicron itself.