# 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.

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

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, 2010-2011 through 2021-2022** 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)
2019-2020 36,000,000 (29,000,000 – 71,000,000) 16,000,000 (13,000,000 – 32,000,000) 390,000 (313,000 – 750,000) 25,000 (18,000 – 79,000)
Preliminary estimates*
2021-2022* 9,000,000 (7,700,000 – 15,000,000) 4,000,000 (3,600,000 – ,300,000) 100,000 (82,000 – 176,000) 5,000 (3,700 – 20,000)

** Estimates are not available for the 2020-2021 flu season due to minimal influenza activity.

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

* Estimates are not available for the due to minimal influenza activity.

#### Supporting Research

Flu-related illness and hospitalization

United States

Global

Visit Flu Burden Averted by Vaccination for CDC estimates of flu-related illness and hospitalization averted by vaccination.