NREVSS: Laboratory Viral Surveillance Guide

The National Respiratory and Enteric Virus Surveillance System (NREVSS) is a laboratory-based surveillance system run by the U.S. Centers for Disease Control and Prevention (CDC). Participating laboratories report weekly totals of the tests they perform and how many were positive, which lets investigators follow when and where respiratory and enteric viruses circulate across the United States. For researchers in public health and infectious disease epidemiology, its core metrics are test volumes and percent positivity.

What it is

NREVSS is a voluntary system in which laboratories send CDC aggregate weekly counts rather than individual patient records. According to CDC, participating laboratories report weekly totals of tests performed, the type of test used for detection, and the number of positive results, along with specimen type, collection location and week of collection.

CDC states that the system was created in the 1980s to monitor seasonal trends in respiratory viruses and was later expanded to include select enteric viruses. It complements syndromic systems that count clinical visits by adding laboratory-detected viral activity.

Who runs it and what it covers

CDC lists the Coronavirus and Other Respiratory Viruses Division, within the National Center for Immunization and Respiratory Diseases (NCIRD), as the content source for the NREVSS dashboard. Reporters are voluntary and include university and community hospitals, state and county public health departments, and commercial laboratories.

Viruses covered

• SARS-CoV-2
• Respiratory syncytial virus (RSV)
• Influenza viruses
• Human parainfluenza viruses, types 1 to 4
• Human metapneumovirus (HMPV)
• Rhinovirus/enterovirus
• Respiratory adenoviruses
• Human coronaviruses (229E, NL63, OC43 and HKU1)
• Rotavirus
• Norovirus

NREVSS, FluView and the national lab network

FluView is CDC’s weekly influenza surveillance report; its companion application, FluView Interactive, lets users explore influenza data in more depth and is updated weekly. CDC describes the virologic side of influenza surveillance as a network of about 100 public health laboratories and about 300 clinical laboratories in all 50 states, Puerto Rico, Guam and the District of Columbia, whose laboratories contribute through either the U.S. Influenza Collaborating Laboratories System or NREVSS.

For clinical laboratories, CDC treats a week-over-week change of 0.5 percentage points or more in percent positive as an increasing or decreasing trend; smaller changes count as stable. CDC derived the threshold from fluctuation during periods of low activity (under 2.0% positivity).

How to search or use it

NREVSS data are explored through an interactive dashboard on the CDC website (cdc.gov/nrevss). Based on CDC’s description of the dashboard:

1. Open the NREVSS dashboard page on cdc.gov.
2. Use “Select a View” to choose national data from all participating laboratories, or to filter by HHS region, surveillance year or virus, and to choose respiratory or enteric virus data.
3. Use “Select Virus” to pick one or more viruses.
4. Filter to one of the ten HHS regions when you need regional detail.

Note that respiratory results on the public dashboard include only nucleic acid amplification tests (NAATs, also called PCR tests). For influenza-specific views, use FluView Interactive. If you plan to compare against epidemiology and public health practice, record which view, virus and period you used so the figures can be reproduced.

Strengths and limits

When incorporating surveillance findings under the CDC program evaluation framework, keep these characteristics in mind:

• Laboratory confirmation (strength): The data count tested specimens and positive detections, so they show which viruses are circulating rather than symptom clusters.
• Percent positivity (strength): Positive tests divided by total tests adjusts for changes in how many tests are performed.
• Voluntary reporting (limit): Participation is voluntary, so coverage depends on which laboratories report and the figures are not population-based incidence.
• Aggregate data only (limit): Weekly totals carry no patient-level clinical details. Investigators who need linked individual records would need a separate arrangement such as a data use agreement with the data holder.
• Tested population (limit): Positivity reflects specimens that were submitted for testing, not all infections in the community. Observational studies that cite such figures can report their methods using the STROBE checklist.

Alternatives

System	What it measures	Who reports
NREVSS	Laboratory test counts and positive results for respiratory and enteric viruses	Voluntary participating laboratories
ILINet	Outpatient visits for influenza-like illness	About 4,000 outpatient healthcare providers each week, per CDC
FluView	CDC’s weekly influenza surveillance report, drawing on several surveillance components	CDC, using data from its surveillance networks

FAQ

What does NREVSS stand for?

NREVSS stands for the National Respiratory and Enteric Virus Surveillance System, operated by CDC.

How does NREVSS differ from FluView?

NREVSS is a laboratory reporting system covering several viruses. FluView is CDC’s weekly influenza surveillance report and interactive application. CDC describes influenza laboratories as contributing through either NREVSS or the U.S. Influenza Collaborating Laboratories System.

What does NREVSS report?

Weekly totals of tests performed, the test type used, and the number of positive results, with specimen type, collection location and week of collection.

Which tests does the public dashboard show?

For respiratory viruses, CDC states that the dashboard includes only nucleic acid amplification tests (NAATs/PCR).

Sources

• Centers for Disease Control and Prevention. (2025, June 18). National Respiratory and Enteric Virus Surveillance System (NREVSS). Checked 2026-11-07. https://www.cdc.gov/nrevss/php/dashboard/index.html
• Centers for Disease Control and Prevention. (2025, December 2). U.S. Influenza Surveillance: Purpose and Methods. Checked 2026-11-07. https://www.cdc.gov/fluview/overview/