Overview
A fundamental role of public health involves tracking and addressing emerging health patterns and risks affecting communities at large. A key method for achieving this is syndromic surveillance, enabling health authorities to rapidly obtain information on increases in patient conditions and signs, even prior to any verified diagnosis or laboratory confirmation—often within just 24 hours of reporting. This capability proves particularly vital as we approach the season for influenza and other respiratory viruses.
Public health’s essential duty includes observing and reacting to health trends and population-wide threats. Syndromic surveillance serves as a vital instrument, permitting officials to swiftly review data regarding surges in patient illnesses and symptoms without needing a confirmed diagnosis or lab test—frequently accessible within 24 hours post-report. This empowers timely responses to dangers and ongoing trend monitoring. Such timeliness is crucial entering flu and respiratory virus periods. Pathogens like influenza, COVID-19, RSV, and similar viruses can surge abruptly, posing greatest risks to infants and seniors, and potentially straining healthcare facilities as history has demonstrated. This piece delivers a comprehensive look at syndromic surveillance, detailing data collection methods, sharing processes, and applications by the Centers for Disease Control and Prevention (CDC) alongside state, tribal, local, and territorial (STLT) health agencies. It also highlights practical instances where these departments apply the data to advance public health outcomes and equity.
The development of syndromic surveillance gained momentum largely due to concerns over bioterrorism and the anthrax contamination of mail after the September 11 attacks on the World Trade Center. Today, its scope has broadened significantly beyond terrorism concerns, with the CDC spearheading the National Syndromic Surveillance Program (NSSP). This program covers a wide array of illnesses, symptoms, environmental dangers, injuries, non-communicable diseases, and additional factors. Daily, the NSSP processes 9.6 million electronic health records from more than 7,200 facilities across every state, as reported by the CDC.
Syndromic surveillance initiates when patients seek medical attention from providers. Primarily, this occurs in hospital emergency departments, though depending on the region, it may incorporate urgent care facilities (increasingly used for cases once directed to ERs), emergency medical services, outpatient settings, or various other providers.
Healthcare providers gather diverse data, generally encompassing chief patient complaints and symptoms, diagnostic codes, demographics, and location details. This data undergoes de-identification prior to transmission to local or state health departments or health information exchanges (HIEs). Note that while termed de-identified or anonymized, such data typically does not satisfy HIPAA’s strict de-identification standards, and re-identification remains a potential concern with all datasets. Providers or HIEs may forward it straight to the CDC’s BioSense platform, or health departments upload it subsequently. BioSense, the CDC’s cloud-hosted system for electronic health data, forms the backbone of the NSSP.
Upon reaching BioSense, data becomes promptly accessible to practitioners via the Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE), supporting analysis, visualization, and teamwork. The rapid availability underscores its worth, aiding swift threat detection and departmental action. Lab-confirmed reports for conditions like flu or COVID-19 might delay days or weeks. Moreover, for scenarios like tracking emergency visits post-wildfires, no specific lab test or diagnosis captures the full threat. By including symptoms and complaints, syndromic data spots emerging issues through pattern recognition without tests or diagnoses.
The CDC offers various case studies showing STLT applications of this data to pinpoint or analyze public health risks. Examples encompass confirming underreported boating injuries in Washington state; examining Idaho emergency data on demographics of those with suicidal thoughts or attempts to inform suicide prevention; and in Nebraska, using it to track overdose patterns, drug trends, and direct prevention initiatives.
Additionally, states analyze their syndromic data internally, often creating public reports or dashboards. These tools assist in observing seasonal disease fluctuations, critical during respiratory illness peaks. For instance, New York City maintains a dashboard detailing emergency visits for respiratory issues from 2016-2025, segmented by zip code. Illinois releases data on ER visits for flu, COVID-19, RSV, and acute respiratory illness. Kansas Department of Health and Environment shares statewide emergency data on gastrointestinal, respiratory, heat-related illnesses, and more. Public access empowers not just officials but communities, providers, schools, and individuals to inform responses and equitable strategies.
Syndromic surveillance’s protective roles are extensive, facilitating early threat identification from infectious diseases, chronic conditions, and environmental factors. It exemplifies effective collaboration between STLT departments and federal entities, with local data sharing revealing jurisdiction-specific insights and CDC tools enabling national pattern detection.
