Table 2. Characteristics of the influenza seasons used for epidemic threshold calculation

Influenza season	Korean method				U.S. method
	Seasons used for the calculation (length*)	Length* of non-influenza period	Mean rate of ILI during non-influenza weeks	SD of ILI during non-influenza weeks	Seasons used for the calculation (length*)	Length* of non-influenza period	Mean rate of ILI during non-influenza weeks	SD of ILI during non-influenza weeks
2018−2019	2015−2016, 2016−2017, 2017−2018 (156)	75	4.63	0.85	2016−2017, 2017−2018 (104)	76	5.70	2.01
2019−2020	2016−2017, 2017−2018, 2018−2019 (156)	64	4.38	0.79	2017−2018, 2018−2019 (104)	74	5.87	2.62
2022−2023	2017−2018, 2018−2019, 2019−2020 (156)	73	3.51	1.15	2018−2019, 2019−2020 (104)	74	4.64	2.91

ILI, influenza-like illness.
Unit: weeks.