Table 1.

The Influenza Severity Scale (ISS).

Domain	Parameter	Level	Score
Demographic	Age group	< 66 years	0
		≥ 66 years	5
	Sex	Male	0
		Female	2
Health history	Smoking status	Never smoked	0
		Former smoker	5
		Current smoker	7
		Unknown	9
	Chronic Pulmonary Diseases	No	0
		Yes	20
	Diabetes mellitus	No	0
		Yes	4
	Vaccination in the current influenza season	Yes	0
		No	1
Clinical presentation	Cough	No	0
		Yes	4
	Sputum production	No	0
		Yes	7
	Shortness of breath	No	0
		Yes	30
Function	Require regular support for activities of daily living	Unknown	0
		No	7
		Yes	18
Total score			100
Risk stratification
Low risk			≤ 30
Moderate risk			> 30 and < 50
High risk			≥ 50