Weekly influenza surveillance overview, 25-31 March 2013 - week 13

Weekly reporting on influenza surveillance in Europe for the 2012–13 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.• Nineteen of 26 reporting countries indicated low-intensity transmission. • Decreasing or stable trends were reported by almost all reporting countries.• The proportion of influenza-positive sentinel specimens remained high (40%) but has continued to decrease since the peak observed in week 5/2013 (61%) and with a considerably lower number of specimens tested.• 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(H1)pdm09 viruses has been 63%. • Thirty-two hospitalised laboratory-confirmed influenza cases were reported by six countries, including one fatality.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 2012–13 influenza season is waning and slowly moving towards its close.