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Respiratory Virus Activity Levels

About

Provides an update on how COVID-19, influenza, and RSV may be spreading nationally and in your state.

Summary

Level of Respiratory Illness Activity

Activity levels determined weekly based on the percentage of visits to enrolled outpatient healthcare providers or emergency departments for fever and cough or sore throat reported to ILINet. Visits can be attributed to a variety of respiratory pathogens that cause these symptoms. Activity levels reflect how the percentage in the most recent week compares to what that jurisdiction typically experiences during low circulation periods. Trend information for the percentages used to calculate activity levels can be found at: National, Regional, and State Level Outpatient Illness and Viral Surveillance (cdc.gov). Refer to data notes for more details.

Wastewater Map

Wastewater (sewage) can be tested to detect traces of infectious diseases circulating in a community, even if people don't have symptoms. You can use these data as an early warning that levels of infections may be increasing or decreasing in your community. COVID-19 wastewater trends may differ from some health outcome findings, such as hospitalization trends, as COVID-19 is causing severe disease less frequently than earlier in the pandemic. Refer to data notes for more details, including important considerations for interpreting wastewater findings such as the inability of wastewater data to determine the source of viruses like influenza A (from humans, animals, or animal products).

* Level based on a small segment (less than 5%) of the population and may not be representative of the state/territory. Read more »

Emergency Department Visits for Viral Respiratory Illness

Weekly percent of total emergency department visits associated with COVID-19, influenza, and RSV. Refer to data notes for more details.

Percent of Tests Positive for Respiratory Viruses

Weekly percent of tests positive for the viruses that cause COVID-19, influenza, and RSV at the national level. Preliminary data are shaded in gray. Refer to data notes for more details.

Data Notes

  • Source: U.S. Outpatient Influenza-Like Illness Surveillance Network (ILINet).
  • Additional information available at: Outpatient Illness Surveillance methods section.
  • This system monitors visits for respiratory illness that includes fever plus a cough or sore throat, (also referred to as influenza-like illness, or ILI), not laboratory confirmed infections; therefore, patient visits due to a variety of respiratory pathogens that cause similar symptoms may be captured.
  • The activity levels compare the mean reported percent of visits due to ILI during the current week to the mean reported percent of visits due to ILI during non-influenza weeks. The 13 activity levels correspond to the number of standard deviations below, at, or above the mean for the current week compared with the mean during non-influenza weeks.
  • This map uses the proportion of visits to enrolled outpatient healthcare providers or emergency departments for respiratory illness to measure the activity level within a state. It does not, however, measure the extent of geographic spread of respiratory illness within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
  • Data collected in ILINet may disproportionately represent certain populations within a state depending on enrolled providers, and therefore may not accurately depict the full picture of respiratory virus activity for the whole state.
  • The data presented in this map is preliminary and may change as more data is received.
  • Differences in the data presented by CDC and state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

The map shows the Wastewater Viral Activity Level for states and territories in the United States. This metric indicates whether the amount of virus in the wastewater for specific respiratory illnesses is minimal, low, moderate, high, or very high. Wastewater monitoring can detect viruses spreading from one person to another within a community earlier than clinical testing, and before people who are sick go to their doctor or hospital. It can also detect infections without symptoms. If you see increased Wastewater Viral Activity Levels of COVID-19, influenza virus, or RSV, it might indicate that there is a higher risk of infection. For more information, see Data Methods.

Data representing less than 5% of the population have a hatching pattern on the map, which is a note of caution that the wastewater viral activity level shown may not be representative of the state or territory. States or territories without sufficient data are indicated as "No data". This can be due to no data reported from the state or territory, or all sites not having the minimum weeks of data available to calculate the wastewater viral activity level.

Data Limitations for Influenza A:

  • Wastewater data cannot determine the source of influenza A viruses. Detections could come from a human or from an animal (like a bird) or an animal product (like milk from an infected cow).
  • Wastewater testing for influenza displayed in these visuals only detects influenza A viruses and does not distinguish between influenza A subtypes (e.g. seasonal influenza A(H1N1) virus, seasonal influenza A(H3N2) virus and avian influenza A(H5) virus).

Data Limitations for RSV: Wastewater data will not include waste that may be disposed of outside the wastewater system, such as from people wearing diapers.

For more data limitations, see Data Methods.

  • Sources: COVID-19 and RSV: National Respiratory and Enteric Virus Surveillance System (NREVSS), a sentinel network of laboratories located through the US, includes clinical, public health and commercial laboratories; additional information available at: https://www.cdc.gov/surveillance/nrevss/index.html. Influenza: Clinical laboratory test results from NREVSS and U.S. World Health Organization collaborating laboratories; more details about influenza virologic surveillance are available here: https://www.cdc.gov/flu/weekly/overview.htm.
  • Data for recent weeks in gray may be incomplete due to delays in reporting. These preliminary may change as more data become available.
  • Data represent laboratory tests performed, not individual people.
  • The data are from across the country in all regions.
  • The percent of tests positive is calculated by dividing the number of positive tests by the total number of tests administered, then multiplying by 100 [(# of positive tests/total tests) x 100].
  • COVID-19: The condition caused by infection with severe acute respiratory syndromic coronavirus type-2 (SARS-CoV-2).
  • RSV and COVID-19 are limited to nucleic acid amplification tests (NAATs), also listed as polymerase chain reaction tests (PCR).
  • Participating laboratories report weekly to CDC the total number of RSV tests performed that week and the number of those tests that were positive. The RSV trend graphs display the national average of the weekly % test positivity for the current, previous, and following weeks in accordance with the recommendations for assessing RSV trends by percent ( https://academic.oup.com/jid/article/216/3/345/3860464).
  • COVID-19 laboratory data are available for download here: https://data.cdc.gov/Laboratory-Surveillance/Percent-Positivity-of-COVID-19-Nucleic-Acid-Amplif/gvsb-yw6g
  • RSV laboratory data are available for download here: https://data.cdc.gov/Laboratory-Surveillance/Percent-Positivity-of-Respiratory-Syncytial-Virus-/3cxc-4k8q

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Content Source:
National Center for Immunization and Respiratory Diseases (NCIRD)