The next COVID vaccines should exclude the original strain of SARS-CoV-2 and exclusively target the Omicron XBB subvariants, according to FDA staff members.
They unveiled their recommendation in a briefing document ahead of Thursday’s meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC), stating that “the totality of available evidence suggests that a monovalent XBB-lineage vaccine is warranted for the 2023-2024 vaccination campaign.”
XBB strains are more immune evasive than prior Omicron subvariants and currently account for about 95% of COVID-19 cases worldwide, the agency staffers noted.
In the U.S., eight XBB strains account for over 98% of the current cases, according to CDC’s Nowcast tracker, including three sublineages under consideration for the fall vaccine: XBB.1.5 in 40%, and the newer XBB.1.16 in 18% and XBB.2.3 in 6% of cases.
Spike proteins of these three sublineages “are similar with few amino acid differences … and available studies suggest little to no further immune evasion from these new substitutions in the XBB.1.16 spike compared to XBB.1.5,” noted FDA staff.