COVID-19 antibody levels after the second vaccine dose by LIPS assay. Levels of nucleocapsid (○) and spike (•) antibodies in 223 patients with HCL/HCLv. COVID-19 antibodies vs levels of circulating normal B cells (A-B), CD4⁺ T-cell counts (C), and plasma IgG levels (D). Linear regression lines are shown. Upper limits of negative are 125 000 and 45 000 light units for nucleocapsid and spike antibodies, respectively.