Purpose
This page includes information about the estimated burden of influenza (flu) from past seasons, including tables of the estimated influenza disease burden (and 95% credible interval [Cr I]) by age group.
Past Seasons
Information on how these estimates are calculated can be found on How CDC Estimates the Burden of Seasonal Influenza in the U.S.
Estimated Number of Flu Illnesses, Medical Visits, Hospitalizations, and Deaths Prevented by Vaccination, by Age Group, 2010-2011 through 2022-2023* 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 | (16,000,000 – 46,000,000) | 10,000,000 | (7,900,000 – 21,000,000) | 280,000 | (190,000 – 1,000,000) | 36,000 | (21,000 – 140,000) |
| 2011-2012 | 9,300,000 | (8,600,000 – 12,000,000) | 4,300,000 | (4,000,000 - 5,600,000) | 130,000 | (120,000 – 180,000) | 12,000 | (10,000 – 23,000) |
| 2012-2013 | 33,000,000 | (26,000,000 – 66,000,000) | 15,000,000 | (12,000,000 – 30,000,000) | 570,000 | (360,000 – 1,800,000) | 42,000 | (25,000 – 110,000) |
| 2013-2014 | 29,000,000 | (24,000,000 – 41,000,000) | 13,000,000 | (12,000,000 - 15,000,000) | 340,000 | (260,000 – 640,000) | 37,000 | (23,000 – 100,000) |
| 2014-2015 | 30,000,000 | (26,000,000 – 39,000,000) | 14,000,000 | (11,000,000 – 18,000,000) | 590,000 | (410,000 – 1,100,000) | 51,000 | (34,000 – 100,000) |
| 2015-2016 | 23,000,000 | (19,000,000 – 32,000,000) | 10,000,000 | (9,000,000 – 14,000,000) | 270,000 | (210,000 – 480,000) | 22,000 | (17,000 – 35,000) |
| 2016-2017 | 29,000,000 | (24,000,000 – 44,000,000) | 13,000,000 | (11,000,000 – 22,000,000) | 490,000 | (370,000 – 830,000) | 38,000 | (28,000 – 60,000) |
| 2017-2018 | 41,000,000 | (35,000,000 – 53,000,000) | 18,000,000 | (16,000,000 – 24,000,000) | 710,000 | (560,000 – 1,100,000) | 51,000 | (36,000 – 95,000) |
| 2018-2019 | 28,000,000 | (24,000,000 – 40,000,000) | 13,000,000 | (11,000,000 – 18,000,000) | 370,000 | (300,000 – 660,000) | 27,000 | (19,000 – 96,000) |
| 2019-2020 | 35,000,000 | (28,000,000 – 70,000,000) | 16,000,000 | (13,000,000 - 30,000,000) | 390,000 | (310,000 – 720,000) | 25,000 | (18,000 – 78,000) |
| Preliminary estimates* | ||||||||
| 2021-2022* | 9,400,000 | (7,800,000 – 15,000,000) | 4,300,000 | (3,600,000 - 7,200,000) | 100,000 | (83,000 – 180,000) | 4,900 | (4,000 – 24,000) |
| 2022-2023* | 31,000,000 | (26,000,000 – 51,000,000) | 14,000,000 | (12,000,000 - 24,000,000) | 360,000 | (290,000 – 670,000) | 21,000 | (18,000 - 97,000) |
** Estimates are not available for the 2020-2021 flu season due to minimal influenza activity.
- Uncertainty interval: Adjusted estimates are presented in two parts: an uncertainty interval [UI] and a point estimate. The uncertainty interval provides a range in which the true number or rate of flu illnesses, medical visits, hospitalizations, or deaths would be expected to fall if the same study was repeated many times, and it gives an idea of the precision of the point estimate. A 95% uncertainty interval means that if the study were repeated 100 times, then 95 out of 100 times the uncertainty interval would contain the true point estimate. Conversely, in only 5 times out of a 100 would the uncertainty interval not contain the true point estimate.