Respiratory Virus Data: Laboratory Testing Data
These charts provide a weekly overview of the percent and number of laboratory tests that are positive for nine respiratory viruses. The trajectory shows whether virus activity was increasing, stable, or decreasing. This visual also show trends in laboratory test results over time for influenza A, influenza B, RSV (respiratory syncytial virus), COVID-19, adenovirus, seasonal coronaviruses (not including SARS-CoV-2/COVID-19), HMPV (human metapneumovirus), parainfluenza, and rhinovirus/enterovirus. Most clinical tests used cannot distinguish between rhinovirus and enterovirus.
Data shown are subject to change and will be updated as more information is available.
How to use the data visualizations
The dashboards on this page are interactive and provide the percent of tests for respiratory viruses that are positive. Users can choose to view the data in these dashboards by using the hover options, changing the dates, or by clicking on virus checkboxes.
The Respiratory Virus Laboratory Test Results Overview section shows summary data ranking the respiratory viruses tested by percent positivity; the virus with the highest percent positivity in the past week is displayed as number 1. Additionally, this visual provides trajectories for each virus, showing whether percent positivity is increasing, decreasing, or stable and a trend line showing the last three years of percent positivity data. Hovering on the trajectory displays additional data.
The Respiratory Virus Laboratory Testing Data section displays two graphs that allow users to view trends in laboratory test positivity and number of tests conducted. The interactive options allow users to examine and compare a variety of viruses. Clicking on the Select viruses check boxes changes the viruses displayed in both the graphs. The date range can also be changed on these graphs. For this visualization, data is available going back to the week of September 7, 2019.
The percent positivity by week is shown as a line graph with the most recent week labeled. Hovering over the lines displays additional information. Increases in test positivity are typically consistent with increasing circulation of that virus in the community.
The number of tests conducted and the number of tests positive by week are also shown. The total number of tests conducted is shown as the lighter color and those that tested positive are overlayed in the darker color; the most recent week is labeled and hovering over the graph displays additional information.
Technical data notes and data sources
Data source: National Respiratory and Enteric Virus Surveillance System (NREVSS).
NREVSS is a sentinel network of laboratories located through the U.S., including clinical, public health, and commercial laboratories. Participating U.S. laboratories voluntarily submit reports to CDC NREVSS detailing the total number of aggregate tests performed each week to detect select respiratory and enteric viruses, as well as the number of positive tests that week. These diagnostic tests are limited to nucleic acid amplification tests (NAATs) or polymerase chain reaction (PCR) tests.
Calculation of percent positivity: The percent of tests positive is calculated by dividing the number of positive tests (for each virus) by the total number of tests administered (for that virus), then multiplying by 100% [(# of positive tests/total tests) x 100%]. The three-week moving average of percent positivity is used in these charts.
Calculation of laboratory trajectories: The virus-specific trajectory based on laboratory testing is a measure of change in the proportion of laboratory tests positive from the previous week to the next week. There are two ways for the laboratory trajectory to be increasing or decreasing.
- The percent change of the percent positivity from the previous week to the current week must be over the minimum threshold, which is 10%, or,
- The percent change must be consistently higher or lower for three consecutive weeks, and the percent change from the first week to third week must be at least 10%.