The story is the same study after study that the COVID bivalent booster fails & there is waning immunity against XBB.1.5 sub-variant clade (the new dominant sub-variant, having displaced BA.5 omicron)

Waning Immunity Against XBB.1.5 following Bivalent mRNA; month 3 for NAb titers (neutralizing antibodies); By month 3, NAb titers to XBB.1 and XBB.1.5 declined essentially to baseline (Lasrado et al.)

SOURCE:

https://www.biorxiv.org/content/10.1101/2023.01.22.525079v1.full.pdf

NAb titers to XBB.1 and XBB.1.5 were similar, suggesting that the F486P mutation confers greater transmissibility but not increased immune escape. By month 3, NAb titers to XBB.1 and XBB.1.5 declined essentially to baseline levels prior to boosting, while NAb titers to other variants declined less strikingly.’