Weekly influenza surveillance overview, 9 March 2012 - week 9

Surveillance report

The 2011-2012 influenza season started later than recent seasons and has been without any clear geographic progression. The following points are noteworthy this week:
Medium or higher intensity has been reported by 18 countries and increasing trends by 11 countries. Bulgaria, Italy and Spain have reported decreasing trends for at least two weeks in a row and are therefore the first three European countries past their epidemic peak this season.
Of 1 606 sentinel specimens tested, 48.0% were positive for influenza virus, the first proper decline this year. Of these sentinel viruses, 91.4% were type A and 8.6% were type B. Only six were A(H1)pdm09 (<1%).
Since week 40/2011, 1 024 SARI cases , including 40 fatalities, have been reported by seven countries. Of these cases, 690 were related to influenza infection – 90% with A(H3), 5% with A(H1)pdm09 and 5% with B viruses.
No resistance to neuraminidase inhibitors (oseltamivir and zanamivir) has been reported so far this season.
Three European countries have now seen a peak in their national influenza season epidemics but the trend is still upward in a number of others. The epidemics remain dominated by A(H3) viruses, but B viruses seem to be on the increase recently.