Child(6) influenza A virus, H1N1 subtype(1) Immunity(1) virus isolation(1) Respiratory tract infections(1) 2019-novel coronavirus(1) Encephalopathy, influenza(1) hepatitis B(1) Disease attributes.(1) Epidemiologic study characteristics as topic(1) pathogen(1) 2019 novel coronavirus(1) influenza A virus(1) COVID-19(1) hematopoietic stem cell transplantation(1) Tomography, X-Ray Computed(1)