LAUSR

BACKGROUND Respiratory illnesses are a major contributor to pediatric hospitalizations, with influenza and respiratory syncytial virus (RSV) causing substantial morbidity and cost each season. We compared the characteristics and outcomes of children 0-59 months of age who were hospitalized with laboratory-confirmed influenza or RSV between 2009 and 2014 in Ontario, Canada. METHODS We included hospitalized children who were tested for influenza A, influenza B, and RSV, and were positive for a single virus. We characterized individuals by their demographics and healthcare utilization patterns, and compared their hospital outcomes, in-hospital cost, and post-discharge healthcare use by virus type and by presence of underlying comorbidities. RESULTS We identified and analyzed 7,659 hospitalizations during which a specimen tested positive for influenza or RSV. Children with RSV were the youngest whereas children with influenza B were the oldest (median ages 6 months [interquartile range {IQR}: 2-17 months] and 25 months [IQR: 10-45 months], respectively). Complex chronic conditions were more prevalent among children with all influenza (sub)types than RSV (31%-34% vs 20%). In-hospital outcomes were similar by virus type, but in children with comorbidities, post-discharge outcomes varied. We observed no differences in in-hospital cost between viruses or by presence of comorbidities (overall median cost: $4,150 CAD [IQR: $3,710-$4,948]). CONCLUSION Influenza and RSV account for large numbers of pediatric hospitalizations. RSV and influenza were similar in terms of severity and cost in hospitalized children. Influenza vaccination should be promoted in pregnant women and young children, and a vaccine against RSV would mitigate the high burden of RSV.