FDA advisers say next round of COVID-19 booster shots should target an XBB variant

An advisory panel to the U.S. Food and Drug Administration voted unanimously on Thursday to recommend that COVID-19 booster shots be updated for the fall to protect solely against one of the three XBB variants that have taken hold in the United States.

Those three XBB variants, which are all sublineages of the omicron variant, are XBB.1.5, XBB.1.16, and XBB.2.3, CNN reported. What will be dropped from the updated vaccines will be protection against the original strain of the virus because experts believe it could contribute to lower vaccine efficacy against newer strains.

"Your immune response likes to react to what it's seen before," David Ho, M.D., a professor of microbiology and immunology at Columbia University whose research was cited in FDA briefing documents, told CNN. "That's why we made the recommendation that if you want to broaden out your antibody responses, it's best to remove the ancestral spike in future vaccines."

Although the FDA will make the final decision on the updated vaccines, it typically follows the advice of its advisory panels.

While infections have declined across the United States, the virus could be a concern next winter, the FDA's vaccine chief Peter Marks, M.D., said as the daylong meeting began, the Associated Press reported. "We're concerned that we may have another wave of COVID-19 during a time when the virus has further evolved, immunity of the population has waned further, and we move indoors for wintertime," he told the panel.

A big question will be who should get the updated boosters, Paul Offit, M.D., a vaccine scientist at the Children's Hospital of Philadelphia and a member of the advisory committee, told CNN before Thursday's meeting. "What's the goal of the vaccine?" he asked. "If the goal of the vaccine is the stated goal, which is protection against severe disease, do you really need a yearly vaccine for otherwise healthy people less than 75? I mean, is this the flu model? Because I would argue it shouldn't be."

It is important to have evidence about whether protection from the COVID-19 vaccine against hospitalization and death is waning and, if so, in which groups, Offit added. In a presentation at the advisory panel meeting, the U.S. Centers for Disease Control and Prevention said there is evidence of waning protection from bivalent boosters against hospitalization, CNN reported.

COVID-19 boosters will likely be offered this fall, once they are redesigned by vaccine makers.

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