Estimating severity of influenza epidemics from severe acute respiratory infections (SARI) in intensive care units

Table 4 SARI in ICU and ILI rates in the Dutch adult population during influenza epidemics

Season	Total Dutch population size (aged 15+ years)^a	Influenza epidemic (week numbers)	Epidemic duration (weeks)	SARI rate^b	ILI rate^b	SARI to ILI ratio^c	Peak SARI^d
Season	Total Dutch population size (aged 15+ years)^a	Influenza epidemic (week numbers)	Epidemic duration (weeks)	SARI rate^b	ILI rate^b	SARI to ILI ratio^c	Week number	peak SARI rate^b
2007/2008	13,399,377	50–52 and 5–9	8	0.66	37.82	0.017	8	0.11
2008/2009	13,469,675	2–6	5	0.52	56.18	0.009	2	0.13
2009/2010	13,562,729	41–48	8	0.57	68.91	0.008	45	0.09
2010/2011	13,662,078	1–7	7	0.63	49.17	0.013	1	0.12
2011/2012	13,748,724	NA	0	NA	NA	NA	NA	NA
2012/2013	13,833,689	1–16	16	1.42	147.79	0.010	6	0.13
2013/2014	13,901,653	5–8 and 10–11	6	0.39	38.2	0.010	8	0.07
2014/2015	13,979,215	49–13 and 15–17	20	1.68	194.16	0.009	7	0.11
2015/2016	14,073,660	53–11	12	1.2	115.41	0.010	6	0.13

SARI Severe acute respiratory infections, GP general practitioner, ILI influenza-like illness, NA Not applicable as there was no retrospectively registered influenza epidemic
^aGiven for January–December of the first mentioned year of each season-year
^bRate was calculated with total 15+ Dutch population size in 2015 (at a scale of 1/10,000)
^cNumber of ICU SARI per expected medically attended ILI in the total adult Dutch population
^dThe highest registered weekly SARI incidence during an influenza epidemic

ISSN: 1364-8535