Week 45/2017 (6-12 November 2017) 

  • Influenza activity across Europe remained at a low level.
  • Overall, 4.5% of individuals sampled, on presenting with ILI or ARI to sentinel primary healthcare sites, tested positive for influenza viruses, which is a slight increase compared to the previous week (1%).
  • Data from 19 countries or regions reporting to the EuroMOMO project indicated that all-cause mortality was at low levels, as expected for this time of the year.
  • Additional information on global influenza activity is available from WHO’s biweekly global updates.

2017/18 season overview 

  • Since week 40/2017, few influenza viruses have been detected in sentinel and non-sentinel specimens.
  • For detections from both sentinel and non-sentinel surveillance systems, most viruses subtyped or assigned to a lineage this season were identified as A(H3N2) and B/Yamagata viruses, respectively.
  • While low in number (n=21), over 80% of the A(H3N2) viruses genetically characterized belong to clade 3C.2a, the vaccine virus clade, as described in the WHO recommendations for vaccine composition for the northern hemisphere 2017–18.

Influenza intensity, spread and dominant virus type/subtype