BTK and B-cell chronic lymphocytic leukemia: Among the few individuals with chronic lymphocytic leukemia treated with novel agents, such as the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib (N = 3) or the B cell leukemia/lymphoma-2 (BCL-2) inhibitor venetoclax (N = 1), only one individual, an individual treated with ibrutinib, had a vaccine-induced anti-spike IgG response above the cutoff of 10 binding antibody units (BAU) per ml.