B2M and B-cell chronic lymphocytic leukemia: CLL disease status, advanced Rai stage (III-IV), elevated serum beta-2 microglobulin levels (β2m >2.4 mg/L), prior therapy, anti-CD20 immunotherapy (<12 months), and intravenous immunoglobulin (IVIg) prophylaxis were all predictive of an inability to mount SARS-CoV-2 NAbs (all p ≤ 0.03).