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.

Massive surge of mRNA expression of clonal B-cell receptor in patients with COVID-19.

BACKGROUND: Antibody production is one of the primary mechanisms for recovery from coronavirus disease 2019 (COVID-19). It is speculated that massive clonal expansion of B cells, which can produce clinically meaningful neutralizing antibodies, occurs in patients who recover on the timing of acquiring adaptive immunity. METHODS: To evaluate fluctuations in clonal B cells and the size of the clones, we chronologically assessed the B-cell receptor (BCR) repertoire in three patients with COVID-19 who recovered around 10 days after symptom onset. RESULTS: We focused on the three dominant clonotypes (top 3) in each individual. The percentage frequencies of the top 3 clonotypes increased rapidly and accounted for 27.8 % on day 9 in patient 1, 10.4 % on day 12 in patient 2, and 10.8 % on day 11 in patient 3, respectively. The frequencies of these top 3 clonotypes rapidly decreased as the patients' clinical symptoms improved. Furthermore, BCR network analysis revealed that accumulation of clusters composed of similar complementarity-determining region 3 (CDR3) sequences were rapidly formed, grew, and reached their maximum size around 10 days after symptom onset. CONCLUSIONS: BCR repertoire analysis revealed that a massive surge of some unique BCRs occurs during the acquisition of adaptive immunity and recovery. The peaks were more prominent than expected. These results provide insight into the important role of BCRs in the recovery from COVID-19 and raise the possibility of developing neutralizing antibodies as COVID-19 immunotherapy.