Comparison of influenza A and influenza B virus infection in hospitalized children

Background: Influenza A and B viruses were cocirculating in Australia in th e winter of 1997. Objective: To compare the clinical and demographic featur es of children with influenza A or influenza B virus infection admitted to a paediatric tertiary referral centre. Methodology: Retrospective chart review of 91 hospitalized children with cu lture-proven influenza A or B virus infection during 1997. Results: Thirty-six (56%) of 64 children with influenza A were under 12 mon ths of age compared with seven (26%) of 27 children with influenza B virus infection (P = 0.02). Influenza B virus infection was more common in childr en with underlying medical problems (P = 0.01). Neurological manifestations were present in eight (12.5%) of 64 children with influenza A and none wit h influenza B virus infection (P = 0.09). There were no significant differe nces in signs and symptoms of children with influenza A and B virus infecti on, in severity of illness or in duration of hospital stay. Conclusions: A greater proportion of children admitted with influenza A vir us infection were under 12 months of age. Influenza B virus infection is as sociated more commonly with underlying medical disorders. It is not possibl e to differentiate between influenza A or B virus infection from presenting clinical signs and symptoms.