TABLE 2.

Influenza‐attributable hospitalization rates estimated in ecologic studies and SARI surveillance studies, 2010–2011 to 2019–2020 influenza seasons

First author, year of publication	Country (data source)	Population	Included diagnoses	Season(s)	Hospitalization rate (per 100,000)	Methods
A Ecologic studies
Goldstein, 2015 31	United States, New York City	50–64 years	Pneumonia & influenza (ICD‐9 480‐488)	2010–11	32.1 (21.9–42.5)	Linear regression, modelled by periodic cubic splines
			All respiratory (ICD 9‐CM 460‐519)		75.6 (51.5–99.3)
Ng, 2019 32	Singapore	50–64 years	Pneumonia & influenza (ICD‐9 480‐487, ICD‐10 J10‐J18)	2010	55.4 (50.6–60.5)	Generalised additive negative binomial regression, cubic smoothing spline function
				2011	48.0 (42.2–53.5)
				2012	60.7 (55.6–66.5)
				2013	52.5 (46.2–58.6)
				2014	56.9 (48.8–65.3)
				2015	55.6 (49.1–61.9)
				2016	83.2 (74.0–91.9)
				2017	89.4 (81.1–97.9)
Rodrigues, 2018 33	Portugal	50–64 years	Pneumonia & influenza (ICD‐9 480‐487, ICD‐10 J10‐J18)	2010–11	21.9 (20.0–23.8)	Autoregressive integrated moving average (ARIMA) model
				2011–12	8.9 (7.4–10.4)
				2012–13	8.7 (7.4–10.0)
				2013–14	5.7 (4.6–6.8)
				2014–15	14.1 (12.5–15.7)
Ang, 2014 34	Singapore	45–64 years	Pneumonia & influenza (ICD‐9 480‐487, ICD‐10 J10‐J18)	2010–2012	29.7 (17.9–43.5)	Negative binomial regression, modelled by natural cubic splines
B SARI surveillance studies
Abdel‐Hady, 2018 35	Oman	50–64 years	ICD‐10 J09‐J18	2012	27 (20.7–33.3)	Hospital discharge + in‐hospital death × age group‐specific influenza positivity
				2013	12.1 (8.0–16.2)
				2014	34.5 (27.7–41.3)
				2015	62.2 (53.2–71.1)
Dawa, 2018 36	Kenya	50–64 years	All	2012–2014	7.3 (6.7–8.0)	Influenza positivity among patients with SARI × SARI hospitalization rates
Emukule, 2019 37	Uganda	50–64 years	Pneumonia as diagnosed by attending clinician	2013–2016	16 (6–27)	Influenza positivity among patients with SARI × SARI hospitalization rates
Refaey, 2016 38	Egypt	50–64 years	All	2013	89 (71–111)	Influenza positivity among patients with SARI × SARI hospitalization rates
Nyamusore, 2018 39	Rwanda	45–64 years	All	2012–2014	12.2 (9.8–14.6)	Influenza positivity among patients with SARI × SARI hospitalization rates
Rabarison, 2019 40	Madagascar	45–64 years	All	2011–2016	20.0 (15.1–24.9)	Influenza positivity among patients with SARI × SARI hospitalization rates
Theo, 2018 41	Zambia	45–64 years	All	2011–2014	25.9 (18.7–33.1)	Influenza positivity among patients with SARI × SARI hospitalization rates

Abbreviations: ICD, International Classification of Diseases; SARI, severe acute respiratory illness.