The impact of influenza and respiratory syncytial virus on hospitalizations for lower respiratory tract infections in young children: Slovenia, 2006-2011.

ABSTRACT

BACKGROUND: Influenza and respiratory syncytial viruses (RSV) are important viral pathogens in childhood. OBJECTIVES: Our aim was to estimate the effect of influenza and RSV on excess hospitalizations for acute lower respiratory tract infections (ALRTI) in children aged≤5. METHODS: Retrospective, population-based study was performed for five seasons (2006-2011). Slovenian national hospital discharge data and surveillance data were used to estimate the effect of influenza and/or RSV on ALRTI hospitalizations (acute bronchiolitis, pneumonia, and acute bronchitis) using rate difference method. RESULTS: An excess was observed in average weekly ALRTI hospitalizations per 100,000 among children aged≤5 in all five seasons during influenza and/or RSV active period. During three seasons, there was higher excess in ALRTI hospitalizations in the period when influenza/RSV cocirculated compared with the RSV period. In pandemic season (2009/2010), the only one without influenza/RSV overlap, excess hospitalization was higher in RSV period. The highest excess of hospitalizations was found among the youngest children (0-5 months old). In all five seasons, acute bronchiolitis was the most common ALRTI recorded in hospitalized young children. CONCLUSIONS: Respiratory syncytial viruses was leading viral pathogen associated with ALRTI hospitalizations in children aged≤5. The cocirculation of influenza virus increased the burden of ALRTI hospitalizations especially in seasons with A(H3) predominance.