Janna-Maija Mattila1, Tytti Vuorinen2,3, Terho Heikkinen1. 1. From the Department of Pediatrics, Turku University Hospital and University of Turku. 2. Department of Clinical Microbiology, Turku University Hospital. 3. Institute of Biomedicine, University of Turku, Turku, Finland.
Abstract
BACKGROUND: Influenza A viruses are conventionally thought to cause more severe illnesses than B viruses, but few studies with long observation periods have compared the clinical severity of A and B infections in hospitalized children. METHODS: We analyzed the clinical presentation, outcomes and management of all children <16 years of age admitted to Turku University Hospital, Finland, with virologically confirmed influenza A or B infection during the 14-year period of 1 July 2004 to 30 June 2018. All comparisons between influenza A and B were performed both within predefined age groups (0-2, 3-9 and 10-15 years) and in all age groups combined. RESULTS: Among 391 children hospitalized with influenza A or B infection, influenza A was diagnosed in 279 (71.4%) and influenza B in 112 (28.6%) children. Overall, there were no significant differences in any clinical features or outcomes, management, treatment at intensive care unit or length of stay between children with influenza A and B, whether analyzed by age group or among all children. As indicators of the most severe clinical presentations, blood cultures were obtained from 101 (36.2%) children with influenza A and 39 (34.8%) with influenza B (P = 0.80), and lumbar puncture was performed to 16 (5.7%) children with influenza A and 11 (9.8%) children with influenza B (P = 0.15). CONCLUSIONS: The clinical severity of influenza A and B infections is similar in children. For optimal protection against severe influenza illnesses, the use of quadrivalent vaccines containing both lineages of B viruses seems warranted in children.
BACKGROUND: Influenza A viruses are conventionally thought to cause more severe illnesses than B viruses, but few studies with long observation periods have compared the clinical severity of A and B infections in hospitalized children. METHODS: We analyzed the clinical presentation, outcomes and management of all children <16 years of age admitted to Turku University Hospital, Finland, with virologically confirmed influenza A or B infection during the 14-year period of 1 July 2004 to 30 June 2018. All comparisons between influenza A and B were performed both within predefined age groups (0-2, 3-9 and 10-15 years) and in all age groups combined. RESULTS: Among 391 children hospitalized with influenza A or B infection, influenza A was diagnosed in 279 (71.4%) and influenza B in 112 (28.6%) children. Overall, there were no significant differences in any clinical features or outcomes, management, treatment at intensive care unit or length of stay between children with influenza A and B, whether analyzed by age group or among all children. As indicators of the most severe clinical presentations, blood cultures were obtained from 101 (36.2%) children with influenza A and 39 (34.8%) with influenza B (P = 0.80), and lumbar puncture was performed to 16 (5.7%) children with influenza A and 11 (9.8%) children with influenza B (P = 0.15). CONCLUSIONS: The clinical severity of influenza A and B infections is similar in children. For optimal protection against severe influenza illnesses, the use of quadrivalent vaccines containing both lineages of B viruses seems warranted in children.