Methodology

How NY Health Watch collects data, calculates threat levels, and updates the site.

Data sources

All disease activity data is sourced from publicly available government datasets. Primary sources include the NYS Department of Health wastewater surveillance network (updated daily for COVID-19, RSV, and influenza), the NYSDOH weekly respiratory surveillance report, the NYSDOH communicable disease case reporting system, NYSDOH arboviral surveillance (West Nile, Eastern Equine Encephalitis), and the NYSDOH Global Health Update weekly report. Annual communicable disease data comes from the NYSDOH Communicable Disease Annual Report.

Threat levels

Each county is assigned one of four threat levels: Low, Watch, Moderate, or High. These are composite assessments based on the highest-priority disease currently active in the county. A county is marked High only when there is an active confirmed outbreak. Moderate indicates one or more diseases with elevated activity above seasonal baseline. Watch indicates conditions that are likely to produce elevated activity in the near term (e.g., peak tick season in a Lyme-endemic county). Low indicates no diseases currently elevated above baseline.

Data freshness

Data freshness varies by disease. Wastewater surveillance data (COVID-19, influenza, RSV, norovirus) is updated daily and reflected on this site within 48 hours. Weekly surveillance reports (Lyme, West Nile, respiratory viruses) are updated every Friday. Annual communicable disease data is updated once per year and is explicitly noted as such on each relevant disease page. Each disease page states its data source and update frequency clearly.

Limitations

This site aggregates and interprets publicly available data but is not a replacement for official NYSDOH communications. Data completeness varies by county and disease. Some counties, particularly in rural upstate New York, have lower surveillance coverage. Annual case data lags current conditions by design. The threat level system is a simplification intended to help the public prioritize — it does not capture all the nuance of official epidemiological assessments. When in doubt, consult NYSDOH directly at health.ny.gov.

Updates

The site is updated at minimum weekly. During active outbreaks, relevant county and disease pages may be updated more frequently. The last-updated date is displayed on each county overlay and disease page.

Questions about methodology: [your email here]