Timing of BNT162b2 vaccine prior to COVID-19 infection, influence disease severity in patients with hematologic malignancies: Results from a cohort study.

The COVID-19 pandemic continues to pose challenges to the treatment of hemato-oncology patients. Emergence of COVID-19 variants, availability of vaccine boosters and antiviral treatments could impact their outcome. We retrospectively studied patients with hematologic malignancies and confirmed COVID-19 during the Omicron outbreak. Of 116 evaluated patients, 16% developed severe or critical COVID-19. Diagnosis of chronic lymphocytic leukemia (CLL) was significantly associated with severe COVID-19 (p = 0.01). The vaccine effectiveness was related to the timing of the vaccine, with patients who received a mRNA vaccine within 7-90 days prior to COVID-19 being less likely to develop severe disease compared to all other patients (p = 0.019). There was no correlation between disease severity and antiviral therapies. Importantly, 45% of patients undergoing active hematological treatment had to interrupt their treatment due to COVID-19. In conclusion, patients with hematologic malignancies are at a considerable risk for severe COVID-19 during the Omicron outbreak, with patients with CLL being the most vulnerable. mRNA vaccines have the potential to protect hematological patients from severe COVID-19 if administered within the previous 3 months. Hematological treatment interruption is a frequent adverse outcome of COVID-19 infection.