COVID-19; Pediatric hematology oncology; rituximab; acquired immune deficiency syndrome; acute myeloid leukemia; aplastic anemia; artery dilatation; artificial ventilation; blood transfusion; bone marrow transplantation; child; clinical article; coronavirus disease 2019; Editorial; flow cytometry; hematologic malignancy; hematology; hematopoietic stem cell transplantation; histiocytosis; human; immunocompromised patient; immunosuppressive treatment; malignant neoplasm; morbidity; mortality; polymerase chain reaction; psychiatric intensive care unit; sickle cell anemia; thalassemia