“Bivalent BA.1 Booster Vaccines Offer Comparable Protection Against Hospitalization with COVID-19 Sub-lineages BQ.1, CH.1.1, and XBB.1.5, Which Do Not Induce More Severe Disease than BQ.1”

https://pubmed.ncbi.nlm.nih.gov/38115965

The bivalent BA.1 booster vaccines provide similar protection against hospitalization with the COVID-19 sub-lineages BQ.1, CH.1.1, and XBB.1.5, and these sub-lineages do not cause more severe disease than BQ.1.