Data Sources
This library explains where Local Health Signal gets its data and what each source is actually good for. We separate fast current-risk signals from slower context layers so the consumer experience can stay simple without hiding the deeper public-health machinery.
How To Read This Library
Current signal first
If you want the fastest answer about what is circulating right now, start with the weekly respiratory and outbreak surveillance feeds.
Context second
Annual vaccination and community-health sources add depth, but they should not be confused with real-time outbreak reporting.
Methods are part of trust
Some feeds are here because they explain why sources disagree or how Local Health Signal processes raw public-health data into something usable.
Fast Current-Risk Signals
These are the feeds most useful for answering “what is going around right now?” on the consumer path.
CDC Acute Respiratory Illness Activity by State
Weekly (Fridays)A broad statewide respiratory-illness signal based on emergency department visits.
Source: CDC · Coverage: All 50 states + DC
CDC FluView / ILINet
Weekly (Fridays)Outpatient influenza-like illness surveillance through the ILINet provider network.
Source: CDC Influenza Division · Coverage: National, regional, and participating state ILINet rows, with some current state reporting gaps
CDC Hospital Respiratory Data (HHS Protect)
WeeklyHospital admission and capacity data used by Local Health Signal for RSV and COVID-19 state pages.
Source: CDC / healthdata.gov · Coverage: National and state-level hospital reporting
JHU Measles Tracking
WeeklyCounty-level measles case counts and outbreak tracking compiled from state and local health department reports.
Source: JHU CSSEGISandData Measles Tracking Team · Coverage: National, state, and county-level
CDC Wastewater Monitoring Program (NWSS)
CDC public dashboards update weekly on Fridays; sampling varies by siteOfficial CDC wastewater monitoring source for community-level viral activity, including COVID-19, influenza A, RSV, measles, A(H5), and monkeypox.
Source: CDC Wastewater Monitoring Program / National Wastewater Surveillance System · Coverage: Municipal wastewater sites across all 50 states, 7 territories, and some tribal communities
Context And Prevention Layers
These sources add local context, vaccination protection, or structural risk, but they are not real-time outbreak trackers.
CDC SchoolVaxView
AnnualKindergarten vaccination coverage rates including MMR, by state.
Source: CDC National Center for Immunization and Respiratory Diseases · Coverage: All 50 states + DC
CDC PLACES: Local Data for Better Health
Annual releaseCity-level chronic disease, prevention, and community health estimates used in Local Health Signal city pages.
Source: CDC · Coverage: City, county, census tract, and place-level estimates
Water Quality And Environmental Health Layers
These sources support the water-quality pilot by separating public water system reports from address-level and building-level tap questions.
EPA SDWIS: Safe Drinking Water Information System
Federal and state reporting cyclesEPA's federal drinking-water database for public water systems, compliance history, violations, enforcement, and system-level context.
Source: U.S. Environmental Protection Agency · Coverage: U.S. public water systems, violations, enforcement, and system characteristics
EPA Consumer Confidence Reports
Annual reports by July 1Annual Consumer Confidence Reports explain local drinking-water sources, detected regulated contaminants, violations, and required public-water-system context.
Source: U.S. Environmental Protection Agency and local public water systems · Coverage: Community water system annual drinking-water reports
EPA UCMR 5: PFAS and Lithium Monitoring
Multi-year monitoring cycle with periodic data releasesEPA's fifth Unregulated Contaminant Monitoring Rule provides national drinking-water occurrence data for PFAS and lithium from participating public water systems.
Source: U.S. Environmental Protection Agency · Coverage: Selected U.S. public water systems monitoring 29 PFAS and lithium
Comparison And Methods Layer
These sources help explain disagreement between feeds or document the processed layers behind the site.
CDC NSSP Emergency Department Surveillance
WeeklyEmergency department visit data for respiratory illness syndromes.
Source: CDC National Syndromic Surveillance Program · Coverage: Most states (participation varies)
CDC NREVSS Lab Surveillance
WeeklyLaboratory surveillance for respiratory viruses including RSV, influenza, and others.
Source: CDC National Respiratory and Enteric Virus Surveillance System · Coverage: National and regional
PopHIVE Ingest / DataHub
WeeklyProcessed CDC respiratory illness surveillance data from the PopHIVE open-source project.
Source: PopHIVE Project · Coverage: National and state-level
Learn more about how we process and combine these sources on our methods page.