Differential immune profiles in elderly patients with non-severe versus severe SARS-CoV-2 omicron variant infection: dysregulation of antibody responses and B-cell subsets

Elderly individuals generate RBD-specific and neutralizing antibody responses after SARS-CoV-2 Omicron variant infection, which correlate significantly with disease severity and infection duration. Clinically, these findings highlight the potential utility of antibody kinetics as prognostic biomarkers for stratifying elderly patients at high risk of severe outcomes, thereby informing tailored intervention strategies and vaccine booster optimization. Furthermore, SARS-CoV-2 Omicron variant infection affects the distribution of B-cell subsets, which may predict the long-term immune reconstitution capacity post-recovery. Notably, elderly patients exhibit pronounced PB expansion, a response pattern that facilitates antibody class-switching to enhance antiviral immunity. Such expansion represents a key immunologic feature in elderly patients with SARS-CoV-2 Omicron variant infection.