[Outcomes of COVID-19 due to omicron variant infection complicated with hematological disorders].

When the omicron variant became the most dominant severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) variant causing coronavirus disease 2019 (COVID-19) in Japan, 11 patients with hematological diseases infected with this new variant were treated at our institution. Among them, four of the five patients who had been treated with chemotherapy progressed to moderate-II COVID-19, and two of them died. In contrast, five of the six patients who did not receive the treatment remained at mild to moderate-I stage of COVID-19, except for a single case progressing to moderate-II COVID-19. While all four patients infused with anti-coronavirus monoclonal antibodies within 8 days after the onset survived, the other two patients, being withheld from treatment or treated later, died. In these two cases, anti-SARS-Cov-2 immunoglobulin G antibodies remained at low titers. Although the omicron variant is considered a less harmful SARS-Cov-2 variant, patients with hematological disorders, particularly those who are immunosuppressed caused by chemotherapy, should be continuously cared for as they remain at a higher risk of severe COVID-19 due to insufficient or delayed anti-viral humoral immunity development. Thus, the rapid introduction of antiviral monoclonal antibodies together with anti-viral reagents may rescue these patients.