children(5) SARS-CoV-2(3) Varicella zoster virus.(3) Surveillance(3) Hospitalization(3) oncology(3) COVID-19(2) outcome(1) Pediatric oncology(1) Africa(1) strategy.(1) CD19 directed therapy(1) immunization(1) seroprevalence.(1) T-cell Response(1) pandemic.(1) global child health(1) Immunity(1) COVID(1) solid tumor(1) tisagenlecleucel.(1) vaccine.(1) Blood Transfusion(1) Prevention and control(1) chimeric antigen receptor(1) developing country(1) hepatitis B(1) pediatric cancer.(1)