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Table 2 Duration, spread and dominant viruses in Europe during eight influenza seasons (1999–2007)

From: Influenza activity in Europe during eight seasons (1999–2007): an evaluation of the indicators used to measure activity and an assessment of the timing, length and course of peak activity (spread) across Europe

Season Duration W-E (R2) S-N (R2) Dominant virus(es)**
1999–2000 12 weeks 0.073 0.058 A(H3N2)
2000–2001 18 weeks 0.016 0.013 A(H1N1)/B
2001–2002 15 weeks 0.331* 0.481* A(H3N2)/B
2002–2003 15 weeks 0.428* 0.005 A(H3N2)/B
2003–2004 19 weeks 0.598* 0.001 A(H3N2)
2004–2005 18 weeks 0.680* 0.250* A(H3N2)
2005–2006 14 weeks 0.032 0.002 A(H3N2) A(H1N1) B
2006–2007 14 weeks 0.060 0.287 A(H3N2)
  1. Spread of influenza based on analysis of peak levels of clinical activity
  2. W-E: West-East spread; S-N: South-North spread
  3. R2: squared correlation coefficient (0.250; 0.331; 0.428; 0.481: moderate correlation; 0.598 and 0.680: strong correlation)
  4. *P < 0.05
  5. **: virus (sub)types are only listed if they represented > 20% of total detections