What to know
CDC uses mathematical models to estimate the impact of flu on the population because is not possible to know the exact number of people who have experienced flu illness in the United States. This is because not everyone who gets sick with flu will seek medical care or be tested for influenza. CDC uses the estimates of the burden of flu in the population to inform policy and communications related to influenza prevention and control.
Estimated Flu Burden
Weekly, preliminary estimates of cumulative in-season flu burden in the United States.
Overall burden of influenza (flu) for the 2022-2023 season was an estimated 31 million flu illnesses.
Overall burden of flu illness for the 2021-2022 season was an estimated 9.4 million flu illnesses.
In 2020-2021, the number of people hospitalized with flu was too low to generate stable estimates.
Overall burden of flu illness for the 2019-2020 season was an estimated 35 million flu illnesses.