Six-month antibody persistence after BNT162b2 mRNA COVID-19 vaccination in patients with CLL/SLL. (A) Response rate among CLL patients (n = 61) and healthy controls (n = 39, P = .079). (B) Response rate by current status of treatment , a pairwise comparisons: treatment-naïve (n = 28) vs on-treatment (n = 14, P = .018), on therapy vs previously treated (n=19, P = .006), treatment-naïve vs previously-treated (P = .665). (C,D) Anti-SARS-CoV-2S titers (U/mL) in patients with CLL/SLL (n = 61) and healthy controls (n = 39), at 2 to 3 weeks and 6 months after second vaccination. (E) Anti-SARS-CoV-2S titers (U/mL) in patients with CLL/SLL according to disease status, at 2 to 3 weeks and 6 months after second vaccination (treatment-naïve, n = 28; on-treatment, n = 14; previously treated, n = 19). (F) Anti-SARS-CoV-2S titers (U/mL) dynamics over time in patients with CLL/SLL dichotomized to weak (shown are anti SARS-CoV-2S titers of patients who achieved titer levels within the lowest quartile of titer levels) and strong (shown are anti SARS-CoV-2S titers of patients who achieved titer levels within the upper quartile of titer levels) initial antibody response, 2 to 3 weeks after second vaccine dose.