COVID-19 vaccines being developed and manufactured for the 2023-2024 campaign should target one of the currently dominant XBB variants, the U.S. Food and Drug Administration's (FDA) staff reviewers said on Monday.
The comments were made in documents posted ahead of Thursday's meeting of a panel of FDA's independent experts, who are expected to make recommendations on what strain an updated COVID-19 booster should target.
An advisory group to the World Health Organization (WHO) in May recommended that COVID-19 booster shots for the year should be updated to target XBB subvariants.
Last year's COVID vaccine boosters in the United States featured both the original strain of the vaccine and Omicron in a so-called bivalent shot.
About 17% of people in the United States received a COVID booster shot in the 2022-2023 vaccination season, according to CDC data that was current through early May.
COVID-related deaths in the United States spiked in January, but have mostly fallen since then. They fell 14.3% in the past week.
Regulators say vaccines need to be updated to deal with the unpredictability of the virus.
"There is no indication that SARS-CoV-2 evolution is slowing down, though immunity appears to be mitigating severe clinical outcomes," the FDA's staff said.
The COVID vaccination campaign should feature a monovalent vaccine targeting either the XBB.1.5, XBB.1.16, or XBB.2.3, the FDA's reviewers said.
XBB subvariants accounted for more than 95% of the circulating virus variants in the United States by early June 2023, they added.
COVID-19 vaccine makers like Pfizer/BioNtech, Moderna Inc and Novavax Inc are already developing versions of their respective vaccines targeting XBB.1.5 and other currently circulating strains.
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