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docs/api/covidcast-signals/nhsn.md

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+---
+title: NHSN ED Visits
+parent: Data Sources and Signals
+grand_parent: Main Endpoint (COVIDcast)
+nav_order: 1
+---
+# National Syndromic Surveillance Program Emergency Department Visits
+{: .no_toc}
+
+* **Source name:** `nhsn`
+* **Earliest issue available:** August 08, 2020
+* **Number of data revisions since 18 Nov 2024:** 0
+* **Date of last change:** Never
+* **Available for:** state, hhs, nation (see [geography coding docs](../covidcast_geography.md))
+* **Time type:** week (see [date format docs](../covidcast_times.md))
+* **License:** [Public Domain US Government](https://www.usa.gov/government-works)
+
+## Overview
+
+[The National Healthcare Safety Network (NHSN)](https://www.cdc.gov/nhsn/index.html) is the nation’s most widely used healthcare-associated infection tracking system.
+This dataset represents preliminary weekly hospital respiratory data and metrics aggregated to national and state/territory levels reported to CDC’s National Health Safety Network (NHSN) beginning August 2020.
+
+Each signal below is derived from one of two following datasets:
+
+- Main: [Weekly Hospital Respiratory Data (HRD) Metrics by Jurisdiction, National Healthcare Safety Network (NHSN)](https://data.cdc.gov/Public-Health-Surveillance/Weekly-Hospital-Respiratory-Data-HRD-Metrics-by-Ju/ua7e-t2fy/about_data)
+- Preliminary: [Weekly Hospital Respiratory Data (HRD) Metrics by Jurisdiction, National Healthcare Safety Network (NHSN) (Preliminary)](https://data.cdc.gov/Public-Health-Surveillance/Weekly-Hospital-Respiratory-Data-HRD-Metrics-by-Ju/mpgq-jmmr/about_data). Signals derived from the preliminary dataset have suffix `_prelim` in their signal names.
+
+Both datasets started reporting data in late 2022. As of May 2024, NHSN received data from 78% of US EDs.
+
+State and nation-level values are pulled directly from the source; HHS-level values are aggregated up from the state level.
+
+
+| Signal                          | Description                                                                                                                                                                         |
+|---------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `confirmed_admissions_covid_ew`              | Total number of patients hospitalized with confirmed COVID-19 captured for the Wednesday of the reporting week **Earliest date available:** 2020-08-08                                                                                                     |
+| `confirmed_admissions_covid_ew_prelim`          | Total number of patients hospitalized with confirmed COVID-19 captured for the Wednesday of the reporting week preliminary data reported to NHSN for the previous reporting week (Sunday – Saturday). <br/> **Earliest date available:** 2020-08-08  |
+| `confirmed_admissions_flu_ew`           | Total number of patients hospitalized with confirmed influenza captured for the Wednesday of the reporting week  <br/> **Earliest date available:** 2020-08-08                                                                                       |
+| `confirmed_admissions_flu_ew_prelim`     | Total number of patients hospitalized with confirmed influenza captured for the Wednesday of the reporting week  preliminary data reported to NHSN for the previous reporting week (Sunday – Saturday).<br/> **Earliest date available:** 2020-08-08 |
+
+## Table of Contents
+{: .no_toc .text-delta}
+
+1. TOC
+{:toc}
+
+## Estimation
+
+All data is weekly such that each reported value represents a total from Sunday to Saturday of the reference week. The `output_signal_name` signal mirrors the `input signal name` field for all geographic resolutions except HHS.
+
+### Geographic weighting
+
+State and nation-level values are pulled directly from the source; HHS-level values are aggregated up from the state level by summing the values of member states.
+
+
+## Missingness
+
+Data for reference dates through April 30, 2024 were reported during a federally-mandated reporting period as specified by the Secretary of the Department of Health and Human Services.
+Data for reference dates May 1, 2024 – October 31, 2024 were voluntarily reported in the absence of a mandate.
+As a result, during this period the total number of hospitalized patients on a subsection of hospitals and may not be fully representative.
+Data for reference dates beginning November 1, 2024 were reported during the current mandated reporting period.
+
+All data and metrics capturing information on respiratory syncytial virus (RSV) were voluntarily reported until November 1, 2024.
+
+
+## Limitations
+
+Between reference dates 2024-05-01 and 2024-10-31, the total number of hospitalized patients on a subsection
+of hospitals and may not be fully representative, since reporting was voluntary.
+See the [missingness section](#missingness) for more context.
+
+Standard errors and sample sizes are not applicable to these metrics.
+
+
+### Differences with HHS reports
+
+?
+
+
+## Lag and Backfill
+
+The signals are currently updated weekly, generally on Friday. Each report adds data for the week prior.
+For example, on Friday, 2024-04-19, the source added new data representing hospitalizations from the week ending 2024-04-13.
+This results in a reporting lag of 6 days from the end of the reference week.
+
+
+## Source and Licensing
+
+This source is derived from the CDC's [Weekly Hospital Respiratory Data (HRD) Metrics by Jurisdiction, National Healthcare Safety Network (NHSN)](https://data.cdc.gov/Public-Health-Surveillance/Weekly-Hospital-Respiratory-Data-HRD-Metrics-by-Ju/ua7e-t2fy/about_data) and
+[Weekly Hospital Respiratory Data (HRD) Metrics by Jurisdiction, National Healthcare Safety Network (NHSN) (Preliminary)](https://data.cdc.gov/Public-Health-Surveillance/Weekly-Hospital-Respiratory-Data-HRD-Metrics-by-Ju/mpgq-jmmr/about_data).
+
+This data was originally published by the CDC, and is made available here as a convenience to the forecasting community under the terms of the original license, which is [U.S. Government Public Domain](https://www.usa.gov/government-copyright).