We conducted a cross‐sectional study of 564 consecutive patients with CML who were tested for anti‐SARS‐CoV‐2 IgG/IgM antibodies at their first outpatient visit between May and early November 2020 in five hematologic centers representative of three Italian regions. This evidence concerns the gene CD40LG and chronic myelogenous leukemia, BCR-ABL1 positive.