COVID-19 Cluster in the Hematology/Respirology Ward of a University Hospital during the Seventh Wave of the SARS-CoV-2 Pandemic in Japan: A Descriptive Study

OBJECTIVE: Patients with hematological malignancies and solid organ tumors reportedly tend to have a more severe coronavirus disease 2019 (COVID-19) trajectory than do those with other diseases. We studied the clinical features and outcomes of nosocomial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during the seventh wave of the pandemic. METHODS: This study retrospectively described the characteristics of COVID-19 clusters involving patients in the hematology/respirology ward of Kochi Medical School Hospital during the seventh wave of the pandemic of SARS-CoV-2. PATIENTS: A total of 40 individuals, including 25 patients and 15 healthcare workers, were studied. The diagnosis of SARS-CoV-2 infection was based on reverse transcription polymerase chain reaction performed on nasopharyngeal samples. RESULTS: Eleven patients had hematological diseases, and 14 had respiratory diseases. Most patients presented with a fever (n=19) and/or sore throat (n=10). Lower respiratory tract symptoms and pneumonia were rather infrequent, occurring in two patients. All patients received antivirals. The maximal severities were mild in 21 patients and moderate in 2. Two asymptomatic patients with SARS-CoV-2 infection did not develop symptoms of COVID-19. Cycle threshold values in nasopharyngeal samples were significantly lower in patients with COVID-19 than in those who were asymptomatic at the time of the diagnosis with SARS-CoV-2 infection. All SARS-CoV-2-infected inpatients recovered or did not develop symptoms of COVID-19. CONCLUSION: COVID-19 vaccination, early or preemptive treatment with antivirals, and intrinsic changes in SARS-CoV-2 may have contributed to the more favorable outcomes in our series than in previously reported nosocomial clusters.