Weekly influenza surveillance overview, 18-24 March - Week 12

Weekly reporting on influenza surveillance in Europe for the 2012–2013 season started in week 40/2012. Active influenza transmission began around week 49/2012 with ILI/ARI rates peaking in almost all countries between weeks 52/2012 and 8/2013.• Nine countries reported wide geographic spread with seven of them reporting medium intensity activity. • Decreasing or stable trends were reported by almost all reporting countries.• 45% of tested sentinel specimens were positive for influenza virus. This proportion has declined since week 5/2013, but still remained at a high level, consistent with continuing significant influenza activity. • Since week 40/2012, 47% of sentinel surveillance specimens testing positive for influenza virus have been type A, and 53% type B. Of the influenza A viruses subtyped, the proportion of A(H1N1)pdm09 viruses has been 63%. • For week 12/2013, 24 hospitalised laboratory-confirmed influenza cases were reported by four reporting countries. In all reporting countries, influenza activity continued to decline or had already returned to baseline levels. After more than three months of active transmission, a long period compared to other years, the 2012–2013 influenza season is waning and slowly moving towards its close.