Methodology

To identify the incidence of the flu in every state, 24/7 Tempo reviewed the percentage of outpatient visits with flu-like illnesses (ILI) during the week ending November 26, 2022 from the latest weekly influenza surveillance report prepared by the influenza division of the CDC. 

Influenza-like illness (ILI) activity levels (minimal, low, moderate, and high) are based on the difference between current and off-season average proportions of outpatient visits to health providers for flu-like illnesses. These off-season baselines range from 1.1% of patients in the Seattle region (Idaho, Oregon, and Washington) to 3.1% in the New York region (New Jersey and New York). States with high activity levels are those where flu cases have exceeded the respective baseline by the most.

ILI includes hospital visits for respiratory conditions such as fever plus a cough or sore throat, not laboratory-confirmed influenza. Regional baselines used by the CDC are the average percent of patient visits for ILI during non-influenza weeks for the previous three seasons plus two standard deviations. 

It is important to note that outbreaks occurring in a single city can cause a state to display high activity levels, and data collected may disproportionately represent certain populations within a state and therefore may not accurately capture influenza activity for the whole state. 

Each state’s 65 and over and 5 and under populations were obtained from the U.S. Census Bureau’s 2021 American Community Survey.