Humoral and T-cell immune responses following second dose and booster vaccination. (A) Plasma IgG antibody binding against the S1 domain of SARS-CoV-2 spike in patients with CLL. (B) Neutralizing antibody response to SARS-CoV-2 RBD (spike). (C) IFN-γ levels were measured from blood samples stimulated with a SARS-CoV-2 peptide cocktail containing antigens Ag1, Ag2, and Ag3 for 24 hours. IFN-γ level of >0.1 IU/mL was evaluated as positive response. Patients with a measurable response marked in red.