‘Covid-19 shots should target XBB variants in 2023-24 campaign’

Updated Covid-19 vaccine boosters need to target one of the currently dominant XBB variants during the 2023-2024 vaccination campaign, the US Food and Drug Administration's (FDA) staff reviewers said yesterday.

The comments were made in documents posted ahead of Thursday's meeting of the FDA's panel of 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 sub-variants.

Last year's Covid-19 vaccine boosters in the US featured both the original strain of the vaccine and Omicron in a so-called bivalent shot.

The Covid-19 vaccination campaign should feature a monovalent vaccine targeting either the XBB.1.5, XBB.1.16, or XBB.2.3, the FDA's staff reviewers said.

XBB subvariants accounted for more than 95 percent of the circulating virus variants in the US by early June, the FDA's staff said in its documents, and the virus' trajectory suggests that XBB.1.16 could be the dominant variant by fall this year.

Studies suggest that bivalent Covid-19 vaccine effectiveness against Omicron sublineages appears to wane over time, the staff said.

Only around 17 percent of people in the US received a Covid-19 booster shot in the 2022-2023 vaccination season, according to CDC data that was current through early May.

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.

- Reuters