Disease Burden of Flu

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

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

Preliminary In-Season Disease Burden Estimates
A person working on a digital chart and looking at data.

Preliminary cumulative burden estimates for the 2019-2020 season have been updated to include information from more recent flu seasons. In-season preliminary burden estimates will resume when enough flu data are collected to make an accurate estimate.

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

graphic of flu burden cases

The burden of flu 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 effects of flu varies, it places a substantial burden on the health of people in the United States each year.

CDC estimates that flu has resulted in 9 million – 41 million illnesses, 140,000 – 710,000 hospitalizations and 12,000 – 52,000 deaths annually  between 2010 and 2020.

Table 1: Estimated Flu Disease Burden, by Season — United States, 2010-11 through 2019-20 Flu 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)
2017-2018 41,000,000 (35,500,000 – 53,000,000) 21,000,000 (18,000,000 – 27,000,000) 710,000 (560,000 – 1,100,000) 52,000 (3,000 – 95,500)
2018-2019 29,000,000 (25,000,000 – 40,000,000) 17,000,000 (11,500,000 – 18,500,000) 380,000 (300,000 – 66,000) 28,000 (19,000 – 97,000)
Preliminary estimates* Estimate 95% UI Estimate 95% UI Estimate 95% UI Estimate 95% UI
2019-2020* 35,000,000 (30,000,000 – 49,000,000) 16,000,000 (14,000,000 – 22,000,000) 380,000 (312,000 – 630,000) 20,000 (18,000 – 80,000)

* Estimates from the 2019-2020 season are preliminary and may change as data are finalized.

Figure 2: Estimated U.S. Flu Burden, By Season

graphic of flu burden by season

Download Flu Burden PowerPoint Presentation Slides ppt icon[PPT – 1 MB]

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