The U.S. Food and Drug Administration wants to simplify the Covid-19 vaccination process to more closely resemble what’s happening with the flu vaccine, according to documents posted online Monday. That could include streamlining vaccine composition, immunization schedules and periodic updates of Covid-19 vaccines.
The FDA said it expects to review circulating strains of the coronavirus at least annually and decide in June which strains to select for the fall season, much like the process to update annual flu vaccines.
In the future, the agency said, most people may need just one dose of the latest Covid-19 shot to restore protection, regardless of how many injections they’ve received before. According to the FDA’s briefing paper for its vaccine advisors, two doses may be needed for people who are very young and have not yet been exposed, who are elderly, or who have weakened immune systems.
The agency is pushing for a shift to just one vaccine formulation instead of a combination of monovalent vaccines – currently used for primary injections and targeting only one strain – and bivalent vaccines – currently used for booster doses and targeting more than one tribe.
The FDA briefing documents do not say whether the annual injection would contain a single strain, two strains, or more. The annual flu vaccine immunizes against four strains.
“This simplification of vaccine formulation should reduce complexity, reduce vaccine administration errors due to the complexity of the number of different vials, and potentially increase vaccine compliance by enabling clearer communication,” the FDA said. .
The agency’s independent vaccine advisors, the Vaccines and Related Biological Products Advisory Committee, will meet Thursday to discuss the future of Covid-19 vaccine regimens and will be asked to vote on whether they recommend parts of the FDA’s plan.
Vaccine experts had mixed reactions.
Dr. Gregory Poland of the Mayo Clinic, a former member of the FDA’s advisory panel of experts, says the first thing it should do is outline what it expects to achieve with annual vaccination.
“They will have to decide what is the purpose of using the current vaccines,” says Poland, who studies how the body responds to vaccines. “If it’s to prevent serious illness and death, we’re already there.”
Before considering the move to annual boosters, he would like to see data on how effective the current updated boosters are against the newest Omicron sub-variants.
“The data that keeps coming out regarding efficacy is prior to the BQ and XBB subvariants,” Poland said.
The committee should also demand full transparency from the FDA and drugmakers when weighing its decisions, he said. He was deeply concerned that the agency had not shared all data on bivalent boosters with the advisory committee in June.
Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, said he sees the plan for an annual update as a balance between what science says is necessary to fight the virus and what is actually practical.
“I think it’s a balance, trying to do what the science says, which is the need for adaptability and flexibility. But because of the practical side, the companies can probably make that switch more than once a year,” he said.
But this plan also has some weaknesses, he notes. Yearly updates are fine as long as the virus continues to evolve incrementally based on previously circulating viruses. But he questions whether the world has enough genomic surveillance to catch a radically different variant emerging out of left field, as Omicron did.
“We don’t have the surveillance mechanisms globally. We don’t have the genomic sequencing worldwide. We don’t have the carefully orchestrated dance that it took decades to build for flu surveillance for coronavirus surveillance,” Hotez said.
Dr. John Wherry, director of the Institute for Immunology at the University of Pennsylvania, has studied how second-line immune defenders called T cells hold up against the coronavirus strains
The answer is that it looks pretty good. While our antibody levels drop within about three months of a booster, our T cells seem to stick around longer — nine months so far — and are thought to be the part of immunity that protects against serious consequences like hospitalization and death.
While there doesn’t seem to be much measurable decline in T cells over time, Wherry supports the FDA’s plan for an annual Covid-19 vaccine.
“Recommending vaccines regularly as part of your routine health care is something we should be doing,” he said. “An annual boost with the vaccine will really help make your T cells fitter, keep them up to date and put them in a position to protect us behind the antibodies.”
This means that the boosters should provide some benefits in the short and long term.