COVID-19 in patients with chronic lymphocytic leukemia: a Moscow observational study.

We describe a retrospective cohort, 156 patients with chronic lymphocytic leukemia (CLL) diagnosed with COVID-19, analyze factors associated with a severe disease course and the effects of various treatment regimens. Anti-SARS-CoV-2 IgG and IgM levels are significantly lower. Patients with CLL are more likely to have a severe course of COVID-19, with IL-6 levels acting as a consistent biomarker of disease severity.