Please note: The Centers for Disease Control and Prevention (CDC) discontinued data collection for Geographic Spread in the 2021-22 season.
Influenza data is collected and analyzed each week between October and May by the Vermont Department of Health to determine the estimated level of geographic spread of flu in the state. The current geographic spread can be found in the most recent Weekly Surveillance Report.
Influenza Activity Geographic Spread Definitions:
No Activity: No laboratory-confirmed cases of influenza and no reported increase in the number of cases of ILI.
Sporadic: Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI.
Local: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state.
Regional: Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state with recent laboratory evidence of influenza in those regions.
Widespread: Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state with recent laboratory evidence of influenza in the state.
Sentinel ILINet Surveillance
This surveillance data is based upon reports submitted by ILINet - a nationwide group of medical offices that act as influenza sentinels. Sentinel providers report the number of patients with an influenza-like illness (ILI) seen by their practices each week. The aggregated ILI data are analyzed as part of our monitoring of statewide ILI activity.
Ten medical practices located throughout the state currently partner with the Health Department as sentinels, with at least one practice located in each of the state’s five influenza surveillance regions.
Join ILINet — Medical professionals in family practices, internal medicine offices, urgent care centers, emergency rooms, college student health centers, and pediatric practices are invited to join ILINet. Learn more about becoming a sentinel provider or call (802) 863-7240.
The Vermont Department of Health Laboratory (VDHL) tests specimens for influenza to identify which strains are currently causing illness in the state. VDHL only tests specimens from sentinel providers and during outbreaks. If your facility is experiencing a flu outbreak, please call the Health Department at (800) 640-4374 or (802) 863-7240.
See lab testing information