PPIB and influenza: In other countries, the reported incidences of H1N1pdm09 influenza are significantly higher than those of seasonal influenza.25,26 In our study, however, the H1N1pdm09 influenza incidence rate in 2009 was comparable with the influenza B incidence rate in 2010, although baseline seasonal influenza rates were unknown because the present study did not cover years prior to 2009.