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, concludes the Weekly Influenza Surveillance Overview for week 13.
Of the 26 countries reporting for week 13/2013, 19 countries reported medium intensity and seven countries reported low intensity of influenza activity. No country reported high intensity, and an increasing trend was only reported by Bulgaria.
Virological surveillance shows that 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 specimens positive for influenza virus have been of type A and 53% of type B. Of influenza A viruses subtyped, the proportion of A(H1N1)pdm09 viruses has been 63%.