ABSTRACT
Chronic lymphocytic Leukemia (CLL) and Monoclonal B-Lymphocytosis (MBL) patients have impaired response to COVID-19 vaccination. A total 258 patients (215 CLL and 43 MBL) had anti-spike levels evaluable for statistical analysis. The overall seroconversion rate for CLL was 94.2% (anti-spike ³50AU/mL Abbott Diagnostics) and for MBL 100%. After 3 doses (post-D3) in 167 CLL patients, 73.7% were seropositive, 17.4% had anti-spike levels 50-999AU/mL, and 56.3% ≥1000AU/mL with a median rise from 144.6AU/mL to 1800.7AU/mL. Of patients seronegative post-D2, 39.7% seroconverted post-D3. For those who then remained seronegative after their prior dose, seroconversion occurred in 40.6% post-D4, 46.2% post-D5, 16.7% post-D6, and 0% after D7 or D8. Following seroconversion, most had a progressive increment in anti-spike antibody level: in CLL after the latest dose, 70.2% achieved anti-spike level ≥1,000AU/mL, 48.1% ≥5,000AU/mL, and 30.3% ≥10,000AU/mL. Neutralization was associated with higher anti-spike levels, more vaccines and earlier COVID variants; 65.3% detected neutralizing antibody against early clade D614G, 52.0% against Delta, and 36.5% against Omicron. COVID-specific T-cell production of IFN-γ occurred in 73.9% and IL-2 in 60.9% of 23 tested, and more consistently with higher anti-spike levels. After multiple vaccine doses, by multivariate analysis, IgM ≥0.53g/L (OR=2.90, p=0.0314), IgG3 ≥0.22g/L (OR=3.26, p=0.0057), and lack of current CLL therapy (OR=2.48, p=0.0574) were independent predictors of positive serological responses. Strong neutralization and T-cell responses had high concordance with high anti-spike levels. Multiple sequential COVID-19 vaccination significantly increased seroconversion and anti-spike antibody levels in CLL and MBL.