Methods for detecting seasonal influenza epidemics using a school absenteeism surveillance system

BMC Public Health

Table 1 Reference dates representing the beginning of each seasonal influenza epidemic investigated in the study

School Year	Influenza Epidemic Reference Date
2008–2009	January 20^th, 2009
2010–2011	December 14^th, 2010
2011–2012	January 9^th, 2012
2012–2013	October 26^th, 2012
2013–2014	November 27^th, 2013
2014–2015	December 8^th, 2014
2015–2016	November 17^th, 2015
2016–2017	December 15^th, 2016
2017–2018	December 6^th, 2017

The reference date was the report date for the second of two laboratory-confirmed influenza cases reported within seven days of each other for the first time in an influenza season

ISSN: 1471-2458