Study population and design. (A) CLL patient groups by treatment (naïve [n = 2], treatment active [n = 7], and off-treatment [n = 6]) and by drugs (BTKi [n = 3], Bcl2i [n = 4], anti-CD20 for less than 12 months [n = 4], and anti-CD20 for more than 12 months [n = 2]). (B) Blood samples were collected before the second (II-D0) and third (III-D0) vaccination and at days 2 (D2), 7 (D7) and 14 (D14) and weeks 4 to 5 (W4-5) after second and third vaccination as indicated by the colored circles. Mean and standard deviation for the number of days between first and second vaccinations was 66 ± 25 days and between second and third vaccinations was 131 ± 43 days. (C) The number of patients who received each vaccine regimen.