Technical note:

• EuroFlu collects clinical and virological data from week 40 to week 39 of the following year
  
  
• Monitoring data presented in the EuroFlu weekly surveillance report are based on data collected during the previous week and entered into the EuroFlu database by Thursday 10:00am (Central European Time)
  
  
• The data presented in the EuroFlu weekly surveillance report are preliminary
  
  
• The networks have two additional weeks to enter their definitive data into the EuroFlu database. This delay is due to communication methods (e.g. if data is received by post) and processing times (e.g. the determination of virus subtypes)
  
  
• Differences may exist between the levels of influenza activity reported in the EuroFlu weekly surveillance report (which presents preliminary data) and the levels in the public EuroFlu maps (which present definitive data)
  
  
• As some of the national reference laboratories participating in EuroFlu do not know the total number of non-sentinel specimens (e.g. specimens from hospitals) that were tested for influenza, EuroFlu does not routinely present the percentage of non-sentinel specimens that are positive for influenza (e.g. for the whole of Europe).
  
  

 Last updated: 15th October 2009