Identifying risk factors for severe omicron infection in allogeneic hematopoietic stem cell transplant recipients with hematologic malignancies

Background: In December 2022, a large-scale epidemic occurred in China due to Omicron variant of SARS-CoV-2. This study explored risk factors for Omicron infection in transplant recipients at our institution and investigated the factors influencing the severity of SARS-CoV-2 Omicron infection among recipients of allo-HSCT. Methods: This single-center study investigated totally 63 allogeneic hematopoietic stem cell transplant patients infected with Omicron variant at the Beijing GoBroad Boren Hospital Transplant Center during December 2022 and analyzed their risk factors. Results: The study included 63 allogeneic hematopoietic stem cell transplant patients who developed Omicron infection. There were 34 mild and 29 moderate to severe cases. Their median age was 22 years (range, 1-65 years), with the male-to-female ratio being 1:1.1. Acute myeloid leukemia (53.97%), acute lymphoblastic leukemia (42.86%), and non-Hodgkin lymphoma (3.17%) were underlying diseases. The median time between HCT and Omicron infection was 8.45 months. Significant predictive factors for moderate to severe Omicron infection included older age (p < .0001), cGVHD (p = .0195), concurrent bacterial infection (p < .0001), low absolute lymphocyte count (p = .026), low CD4/CD8 ratio (p = .0091), high CRP (p < .0001), high serum ferritin (p = .0023), high D-dimer (p < .0001), low CD4 absolute count (p = .0057), and low B-cell absolute count (p = .0154). A moderate to high HCT-CI score tended to be associated with moderate to severe infection (p = .0596). Conclusion: This study indicates that risk factors for severe Omicron infection include certain clinical characteristics, such as age, cGVHD, and inflammatory response.