Fig. 1From: Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004–2017Number of laboratory-confirmed influenza type A and B infections by season in Italy, during the study period (2004/2005–2016/2017). Curves of the Influenza-like illness (ILI) incidence rate (× 1000 population served) are also shown for each epidemic season, by weekBack to article page