The Vermont Department of Health monitors flu activity in the state throughout the year using different surveillance methods and creates a report. Influenza surveillance is a collaborative effort among the Centers for Disease Control & Prevention, state health departments, health care providers, laboratories, clinics, and emergency departments. 

Learn more about influenza surveillance in the United States (CDC)

Did you know?

The 2025-2026 flu surveillance season will start the week of September 28, 2025. The weekly Influenza Surveillance Report gives a snapshot of emergency room visit, sentinel provider, lab and outbreak data. Weekly monitoring reports for this season will begin on October 10, 2024 and continue through May 29, 2026. 

Weekly seasonal surveillance will resume on September 28, 2025.

2025-2026 Weekly Flu Surveillance Reports
 
MMWR Week 20 report to be published 10/10/25
Previous Year End-of-Season Reports
 
2023-2024
2022-2023
2021-2022
2020-2021
2019-2020
2018-2019

Geographic Spread

Please note: The Centers for Disease Control and Prevention (CDC) discontinued data collection for Geographic Spread in the 2021-22 season.

This information is provided to help understand past-season reporting.

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.

Eight 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.

Laboratory Testing

The Vermont Department of Health Laboratory (VDHL) tests specimens for influenza to identify which strains are currently causing illness in the state. Specimens may be requested for outbreak surveillance. 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

 

Topics:
Flu
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