A mid-seasonal influenza risk assessment shows that type A viruses, especially A(H1N1)pdm09, are the dominant strains for European Union countries this year.
The assessment also suggests the same strain has caused many hospitalizations for serious influenza cases. These have severe outcomes for the risk groups and for young adults who are otherwise healthy.
A similar mid-season severity pattern is expected in other nations as the influenza season continues.
In E.U. nations, seasonal influenza began in Week 52 last year. The Netherlands confirmed that there was a regional spread of the flu. Sweden also notified health officials that it saw widespread activity of the virus.
Overall, A(H1N1)pdm09 is the most dominant strain for this season. However, B influenza viruses were also strong in four nations, and another three nations had even A and B virus distribution.
The B viruses are expected to become stronger later, gaining dominance by the season’s end. This is based on earlier seasons, when B strains were the most dominant during the latter half of the influenza season.
Most of the influenza patients needing intensive care fell sick with the A(H1N1)pdm09 strain. Approximately 61 percent of these patients are between 15 and 64 years old. This is a significant difference from the 2014-15 season, which show dominance from the A(H3N2) virus that infected more elderly people.