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 – 2023

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 9.3 million – 41 million illnesses, 100,000 – 710,000 hospitalizations and 4,900 – 51,000 deaths annually between 2010 and 2023.

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

Estimated U.S. Influenza Burden, By Season (2010-2023)

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

Supporting Research