Surveillance updates, advisories, and confirmed outbreaks: what's the difference
Public Health Trace's Health Updates feed shows several different kinds of CDC product side by side, each labeled with its own badge. This guide explains what each label means and, importantly, which of them are CDC's own terms versus Public Health Trace's own organizing labels.
CDC's own Health Alert Network message types
CDC's Health Alert Network (HAN) is, in CDC's own words, "CDC's primary method of sharing cleared information about urgent public health incidents" with clinicians, health departments, and public health labs. CDC defines (among its message types):
- Health Alert
- Conveys the highest level of importance about a public health incident.
- Health Advisory
- Provides important information about a public health incident.
- Health Update
- Provides updated information about a public health incident.
Public Health Trace shows a HAN message under the single badge Health advisory, regardless of which of CDC's own HAN message types it actually is. This is a deliberate simplification, not a claim that CDC uses the word "advisory" for all of them.
Surveillance updates: periodic reporting, not an event
CDC separately publishes periodic surveillance reports -- for example, FluView, CDC's weekly influenza surveillance report -- that describe ongoing activity levels rather than a single incident. Public Health Trace labels these Surveillance update. When a source explicitly and literally classifies its own activity level as elevated (for example, a report that states activity is "high" or "elevated," not Public Health Trace's own interpretation of a number), Public Health Trace shows Elevated activity instead for that specific report -- this only ever happens from the source's own literal classification text, never from Public Health Trace judging the numbers itself.
Active investigations and confirmed outbreaks
Active investigation and Confirmed outbreak are two of Public Health Trace's own category labels for a record tracking a specific, identified outbreak event -- which label applies is set per data source, based on what kind of record that source tracks, not computed from whether the investigation happens to be open or closed on a given day (that's a separate concept -- see below). These correspond to CDC's own multistate outbreak investigation process: the same 7-step process (detect, define a case, generate hypotheses, test them, confirm the source, stop the outbreak, and decide it's over) described in CDC's Multistate Foodborne Outbreaks: Investigation Steps.
Whether a specific record is still open or has been resolved is a separate, independent fact Public Health Trace tracks (its lifecycle status) -- see how to read an outbreak investigation for exactly how that's computed and displayed. A record's type badge (what kind of CDC product it is) and its lifecycle status (whether it's still active) are never the same thing.
Travel notices
CDC's Travel Health Notices are a separate CDC system with its own four-level scale, unrelated to the investigation-status concept above. Public Health Trace labels these Travel notice and shows CDC's own level directly, rather than mapping it into any of the categories above.
Why this matters
These badges tell you what KIND of CDC product a record is, not how serious or urgent it is on their own -- a Surveillance update and a Confirmed outbreak are both real, but they answer different questions ("how's this season going" versus "did this specific outbreak happen"). This is Public Health Trace's own organizing scheme for making different CDC products comparable in one feed; CDC itself does not publish a single, unified category system across HAN, FluView, and its outbreak investigations. Always check the official source, linked from every record, for the agency's own framing.
Limitations: only one of Public Health Trace's registered CDC surveillance sources is publicly enabled as of this writing (see data sources for current status), so not every category above may show real examples yet.