The 2011–2012 influenza season started late and has been without any clear geographic progression. The following points are noteworthy this week:
• Medium or higher intensity has been reported in 20 countries, decreasing trends in ten countries and increasing trends in only three countries.
• Of 1 433 sentinel specimens tested, 43.2% were positive for influenza virus, the second decline in a row this year, suggesting that the peak of the epidemic at European level has passed. Of these sentinel viruses, 85.1% were type A and 14.9% were type B. This is the highest percentage of B viruses so far this season.
• Since week 40/2011, 1 238 SARI cases, including 51 fatalities, have been reported by seven countries. Of these cases, 873 were related to influenza infection – 97.4% with A viruses.
• No resistance to neuraminidase inhibitors (oseltamivir and zanamivir) has been reported so far this season.
This is the second consecutive week with a decrease in the proportion of positive sentinel samples. This fact and the reported national trends indicate that the peaks of the epidemics have passed in many, but by no means all EU/EEA countries. The epidemics remain dominated by A(H3) viruses, but B viruses seem to have been increasing late in the season.