Biological & Public Health
Respiratory Illness Activity
ARI/ED is an acute respiratory illness activity signal that reflects emergency department respiratory diagnosis activity by state.
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Quick answer / What to check next
Quick answer
ARI/ED is an acute respiratory illness activity signal that reflects emergency department respiratory diagnosis activity by state.
What this signal means
ARI/ED is broader than one pathogen, so it can add context when respiratory illness activity is increasing even if the driver is not limited to COVID-19, flu, or RSV.
What to check on HazardNow
activity level, state, source week, and whether the signal is High or Very High.
Verify with official source
CDC Respiratory Illnesses
Quick read
- Useful for
- ARI/ED is broader than one pathogen, so it can add context when respiratory illness activity is increasing even if the driver is not limited to COVID-19, flu, or RSV.
- Watch
- activity level, state, source week, and whether the signal is High or Very High.
- Confirm with
- CDC Respiratory Illnesses and CDC data portal
- Remember
- Emergency-department diagnosis activity can lag, depends on care-seeking behavior and reporting, and should not be treated as diagnosis or medical advice for an individual.
How to read ARI/ED
ARI/ED is useful because emergency-department respiratory activity can show broader respiratory illness burden, but it is not a pathogen-specific test and is not a patient-level diagnosis.
- Broader than one pathogen.
- Reflects emergency-department respiratory diagnosis activity.
- High and Very High contribute to Biological elevated status.
- Data cadence and source lag can affect freshness.
Visual reference
Respiratory illness activity signal map
Read the signal as one layer in a larger source stack, not as a standalone instruction.
Official sources to verify
Use these links to verify current source text, update timing, and agency caveats.
Last reviewed: . This page explains general preparedness information and does not replace official instructions.
FAQ
Is ARI/ED tied to one pathogen?
No. It is a broader acute respiratory illness activity signal, so it should be read alongside wastewater and hospital data.
What counts as elevated?
High and Very High activity contribute to the Biological elevated status under the current default rule.
Does Low mean no illness exists?
No. Low or Very Low means HazardNow does not detect an elevated ARI/ED signal under current rules.
Related terms
Check the live HazardNow dashboard
Use this page to understand Respiratory illness activity. Use the live dashboard to see current alerts, infrastructure stress, weather, wildfire, travel, public-health, supply-chain, and stability indicators in one place. Focus on biological-surveillance, wastewater-surveillance, hospital-respiratory-admissions in the live view.