Fig. 3.

Evolutionary dynamics of the HA1 and NA genes from A(H1N1)pdm09 strains isolated in Sendai. a The number of A(H1N1)pdm09 cases in Epi-week since August 2009 (blue bar) and purple box indicated peak at around 4–5th Epi-weeks in 2011 from the database of Viral Respiratory Infection Surveillance conducted by Department of Virology, Tohoku University, Sendai city. b Changes in the genetic diversities of the HA1 and NA genes during 2009–2011 from Sendai. The x-axis is the year, and the y-axis is the relative genetic diversity. The thick solid black line is the median estimate, and the pale blue lines show the upper and lower bounds of the 95 % HDP interval