SARS-CoV-2 breakthrough infections following inactivated vaccine vaccination induce few neutralizing antibodies against the currently emerging Omicron XBB variants.

•Inactivated vaccine breakthrough infection with ancestral variants induced nearly undetectable nAbs against XBB variants.•Inactivated vaccine breakthrough infection with Omicron BA.1 or BA.5 evoked very weak nAbs against XBB variants.•BA.5 infection induced higher nAbs against XBB variants than BA.1 infection.