Abbreviation: NDB, National Database of Health Insurance Claims and Specific Health Checkups of Japan.
1) Seasons for influenza incidence estimation were between week 36 in 2010 and week 35 in 2011; between week 36 in 2011 and week 35 in 2012; and between week 36 in 2012 and week 13 in 2013. Seasons for the number of influenza patients were between September 2010 and August 2011; September 2011 and August 2012; and September 2012 and March 2013. Seasons for NDB coverage were March 2011, March 2012, and March 2013.
2) Influenza incidence estimates and numbers of influenza patients have been published previously [
8].
3) NDB coverages were obtained from a published report [
9].
4) The ratio was the influenza incidence estimate divided by the number of influenza patients and the NDB coverage.