An Epidemiological Study to Investigate the Characteristics of RSV Infection in Adult Hematopoietic Cell Transplant Recipients or Hematological Malignancies Patients in Tianjin HI (Hematology Institute)

Inclusion Criteria: * 1\) Aged ≥ 18 years old. 2) Receiving hematopoietic stem cell transplantation; OR being diagnosed with hematological malignancies (including but not limited to leukemia, lymphoma, and multiple myeloma) and receiving chemotherapy. 3\) New onset of respiratory symptoms; OR exacerbation of existing chronic respiratory symptoms (such as previously diagnosed chronic runny nose, seasonal allergies, chronic lung disease, etc.). 4\) Willing to sign an informed consent form, able to understand and willing to follow the study protocol. Exclusion Criteria: * Unwillingness to sign an informed consent form.