Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induced COVID-19 infections are showing an explosive increase in China starting in late 2022. SARS-CoV-2 infections are characterized by an initial viral replication followed by an inflammatory phase with lymphocyte depletion in severe patients.~Past studies have shown that SARS-CoV -2 is detectable in the blood of 8%-15% of patients and that viremia occurs in the first 2-3 days after the onset of symptoms. EBMT, WMDA and other organizations have suggested that COVID-19 positive donors must be excluded or delayed from donation for safety reasons.~However, there have not been any reports of transmission from donor to recipient in blood product transfusion or cell therapy. In the only reported cases of allogeneic HSCT from SARS-CoV-2 positive donors, there was also no evidence of recipient infection from the graft.~In the current situation where the vast majority of people are infected with COVID-19 in the short term, many patients, such as those with leukemia, are in urgent need of transplantation due to the aggressive， hard-to-control，underlying disease. The investigators established this observational clinical trial to investigate whether COVID-19 is transmitted through stem cells and whether COVID-19 positive donors have an impact on early hematopoietic reconstitution and immune reconstitution in recipients.
This study was conducted to observe whether COVID-19 can be transmitted through stem cell transplantation and whether COVID-19-positive donors have an effect on early hematopoietic reconstitution and immune reconstitution in the recipients.