Delphi V5 API

This is the documentation for accessing Delphi’s epidemiological data streams via the new V5 API. These pages focus on the properties of the data, whereas interactive, endpoint-level documentation is available on the Delphi V5 API Landing Page.

Get updates: Delphi operates a mailing list for users of the API. We will use this list to announce changes, corrections to data, and new features. We strongly encourage all users to subscribe. This is separate from signing up for an API key

Table of contents

  1. Delphi V5 API
    1. Overview of V5 Endpoints
    2. Migrating from Legacy APIs
    3. Authentication and Rate Limits
    4. Accessing the Data
    5. Current Data Sources

Overview of V5 Endpoints

Unlike the COVIDcast endpoints, V5 has three categories of data access under the /epidata/v5 route prefix:

  • /archive/ fetches all snapshots of a dataset prior to a point in time. Each row represents a “diff” (when the value for a specific key changed).
  • /snapshot/ time travels to how a dataset looked at a point in time.
  • /aux_data/ accesses source-specific auxiliary tables containing metadata, laboratory protocols, or additional static keys (e.g., NWSS wastewater facility descriptions).

Additionally, various metadata routes are available for querying schema columns, active signals, geographic types, and distinct values. See the V5 Metadata documentation for more details.

Migrating from Legacy APIs

Many database and query patterns in the legacy API (the COVIDcast endpoint) emerged from the rapid demands of the COVID-19 response. However, this legacy setup introduced critical bottlenecks. To address those limitations, the V5 API improves data quality, speeds up development times, and enhances query performance.

Authentication and Rate Limits

Anyone may access the Epidata API anonymously without providing any personal data. Anonymous API access is currently rate-limited and restricted to public datasets. The rate limits are 60 requests/hour general, with an additional limit of 5 requests/minute on /archive/ and 3 requests/minute on /snapshot/.

You can register a free API key to remove these limits. If you regularly or frequently use our system, please consider using an API key even if your usage falls within the anonymous limits. API key usage helps us understand how our tools are used, which informs our future research, data partnerships, and funding.

Endpoints that require an API key are marked with a 🔒 lock icon. You can use the Authorize button at the top of the Delphi V5 API Landing Page to set your key either as an HTTP header or query parameter.

For more information about how we use the data you provide us through your registration and API request activity, see our Privacy Statement. At any time, you may submit a Deletion Request to have us deactivate your key and destroy all information associating that key with your identity.

Accessing the Data

Modern Delphi API clients (R epidatr and Python epidatpy) support V5 queries natively. You can also explore and test endpoints interactively on the Delphi V5 API Landing Page.

Current Data Sources

Please note that not all endpoints and sources from the legacy API have been migrated to the V5 API. The currently accessible sources are:

Source Code Name Description
nssp NSSP ED Visits Emergency department visits associated with COVID-19, Influenza, and RSV.
nhsn NHSN Hospitalizations Hospital respiratory admissions data reported to the National Healthcare Safety Network.
pophive Epic Cosmos by Pophive Population-weighted claims aggregations representing outpatient activity.
nwss NWSS Wastewater National Wastewater Surveillance System PCR target concentrations.
claims_data_outpatient Outpatient Claims Outpatient medical claims visits.
claims_data_inpatient Inpatient Claims Inpatient medical claims admissions.

For a complete index of all signals, geography levels, and licenses, see V5 Sources and Signals.

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