Spike antibody levels with or without prior exposure to COVID-19, and spike antibody decrease over time. (A) Spike antibody levels without (n = 191, ) vs with (n = 43, •) evidence of prior COVID-19 exposure. Included in the 43 patients with evidence of prior COVID-19 exposure were 4 (•) who tested positive by polymerase chain reaction or rapid-antigen tests but had negative nucleocapsid antibodies for COVID-19. (B) Half-lives of decreases in COVID-19 antibody levels over time compared for patients on ibrutinib (n = 4, ▼) or anti-CD20 mAbs (n = 14, ▲) vs other treatments (n = 17, ▵).