Humoral and cellular immune response in patients with hematological disorders after two doses of BNT162b2 mRNA COVID‐19 vaccine: A single‐center prospective observational study (NCT05074706)

Hematological patients at higher risk of severe COVID‐19 were excluded from the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccine trials. In this single‐center observational prospective study (NCT05074706), we evaluate immune response in the hematological patients followed at the Hematological Division of San Gerardo Hospital, Monza (Italy) deemed to be severely immunosuppressed after vaccination with two doses of the BNT162b2 vaccine. Anti‐SARS‐CoV‐2 immunoglobulin G titers above the cutoff value of 33.8 BAU/ml were detected in 303 (80.2%) out of the 378 patients enrolled. Patients with lymphoproliferative disorders had a significant lower probability of immunization (43.2% vs. 88.4%, p