Disease Burden of Influenza

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Each year CDC estimates the burden of influenza in the U.S. CDC uses modeling to estimate the number of influenza illnesses, medical visits, flu-associated hospitalizations, and flu-associated deaths that occur in the U.S. in a given season. The methods used to calculate these estimates are described on CDC’s webpage, How CDC Estimates the Burden of Seasonal Influenza in the U.S.

CDC uses the estimates of the burden of influenza in the population and the impact of influenza vaccination to inform policy and communications related to influenza.

How CDC Estimates the Burden of Flu

Why CDC Estimates the Burden of Flu

Past Season Estimates

Frequently Asked Questions about Estimated Flu Burden

Preliminary In-Season Disease Burden Estimates

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The preliminary cumulative burden estimates for the 2019-2020 season have been released. In-season preliminary burden estimates are scheduled to resume for the 2020-2021 season this winter.

Flu Burden Averted from Vaccination

CDC estimates the burden of flu and the impact of annual flu vaccination in the U.S using a model that estimates the numbers of flu illnesses, medical visits and hospitalization prevented by vaccination.

Figure 1: Estimated Range of Annual Burden of Flu in the U.S. from 2010 – 2020

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The burden of influenza disease in the United States can vary widely and is determined by a number of factors including the characteristics of circulating viruses, the timing of the season, how well the vaccine is working to protect against illness, and how many people got vaccinated. While the impact of flu varies, it places a substantial burden on the health of people in the United States each year.

CDC estimates that influenza has resulted in between 9 million – 45 million illnesses, between 140,000 – 810,000 hospitalizations and between 12,000 – 61,000 deaths annually since 2010.

Table 1: Estimated Influenza Disease Burden, by Season — United States, 2010-11 through 2019-20 Influenza Seasons
	Symptomatic Illnesses		Medical Visits		Hospitalizations		Deaths
Season	Estimate	95% U I	Estimate	95% U I	Estimate	95% U I	Estimate	95% U I
2010-2011	21,000,000	(20,000,000 – 25,000,000)	10,000,000	(9,300,000 – 12,000,000)	290,000	(270,000 – 350,000)	37,000	(32,000 – 51,000)
2011-2012	9,300,000	(8,700,000 – 12,000,000)	4,300,000	(4,000,000 – 5,600,000)	140,000	(130,000 – 190,000)	12,000	(11,000 – 23,000)
2012-2013	34,000,000	(32,000,000 – 38,000,000)	16,000,000	(15,000,000 – 18,000,000)	570,000	(530,000 – 680,000)	43,000	(37,000 – 57,000)
2013-2014	30,000,000	(28,000,000 – 33,000,000)	13,000,000	(12,000,000 – 15,000,000)	350,000	(320,000 – 390,000)	38,000	(33,000 – 50,000)
2014-2015	30,000,000	(29,000,000 – 33,000,000)	14,000,000	(13,000,000 – 16,000,000)	590,000	(540,000 – 680,000)	51,000	(44,000 – 64,000)
2015-2016	24,000,000	(20,000,000 – 33,000,000)	11,000,000	(9,000,000 – 15,000,000)	280,000	(220,000 – 480,000)	23,000	(17,000 – 35,000)
2016-2017	29,000,000	(25,000,000 – 45,000,000)	14,000,000	(11,000,000 – 23,000,000)	500,000	(380,000 – 860,000)	38,000	(29,000 – 61,000)
Preliminary estimates*	Estimate	95% UI	Estimate	95% UI	Estimate	95% UI	Estimate	95% UI
2017-2018*	45,000,000	(39,000,000 – 58,000,000)	21,000,000	(18,000,000 – 27,000,000)	810,000	(620,000 – 1,400,000)	61,000	(46,000 – 95,000)
2018-2019*	36,000,000	(31,000,000 – 45,000,000)	17,000,000	(14,000,000 – 21,000,000)	490,000	(390,000 – 770,000)	34,000	(26,000 – 53,000)
2019-2020*	38,000,000	(34,000,000 – 47,000,000)	18,000,000	(15,000,000 – 22,000,000)	400,000	(350,000 – 500,000)	22,000	(18,000 – 29,000)