Weeks 31-35/2018 (30 July–2 September 2018)

  • Influenza activity was at inter-season levels.
  • Of all the samples from primary health care settings only one tested positive for influenza virus.

2017/18 season overview 

  • Aggregated regional data indicated that influenza viruses circulated at high levels from week 52/2017 through 12/2018 (based on increased proportions of sentinel specimens – 40% and above – testing positive for influenza viruses). This was longer than in recent seasons and may have contributed to the burden observed during the season.
  • The majority of influenza viruses detected were type B, representing a high level of circulation of influenza B viruses compared to recent seasons. B/Yamagata lineage viruses greatly outnumbered those of the B/Victoria lineage. 
  • Different patterns of dominant influenza virus types and A subtypes were observed between the countries of the Region.
  • While low in numbers, characterized A(H3N2) viruses were reported mainly as clade 3C.2a (57%) and subclade 3C.2a1 (42%), while 45% of B/Victoria lineage viruses fell in a subclade of clade 1A viruses that are antigenically distinct from the 2017–2018 season trivalent vaccine component. 
  • The majority of severe cases were due to influenza type B virus infection and occurred mostly in persons older than 15 years of age. 
  • All-cause excess mortality was increased from December 2017 through March 2018 and was most pronounced among individuals aged 65 years and above, though individuals in the age group 15–64 years also showed marked excess mortality. EuroMOMO. Click here for more information
  • Interim results from 5 European studies indicated 25% to 52% vaccine effectiveness against any laboratory-confirmed influenza virus infection.

Influenza intensity, spread and dominant virus type/subtype