Univariate and multivariate analysis of serological responses. OR for positive serological response (antispike antibodies ≥1000 AU/mL) to COVID-19 vaccine calculated by univariate (A) and multivariate (B) logistic regression models. Biological and clinical factors, using univariate models, associated with zero responders (>4 doses but remain antispike antibodies <50 AU/mL) (C), late responders (antispike antibodies <1000 AU/mL after 3 doses but increased to >1000 AU/mL after the fourth dose) (D), high responders (antispike antibodies ≥20 000 AU/mL at any point after their first dose) (E). Any analysis of IgG levels (or IgG subclasses) excluded patients on IgRT. All patients were treated with Bruton tyrosine kinase inhibitor (BTKi) received ibrutinib. P < .2 was used as the cutoff value for the above models. Pre-vax, prevaccination.