Mass General Brigham relies on a measure from the Center for Disease Control and Prevention’s (CDC) U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet).
ILINet has data from all 50 states, Puerto Rico, the District of Columbia, and the U.S. Virgin Islands. More than 110 million patient visits were reported during the 2022–23 season.
ILINet monitors to see how common virus illness symptoms are. These are the symptoms of fever plus cough or sore throat. CDC provides this data broken down by geographic region. The country is divided into 10 regions. All Mass General Brigham locations are within Region 1.