The Delphi Epidata API provides real-time access to epidemiological surveillance data for influenza, COVID-19, and other diseases from official government sources such as the Centers for Disease Control and Prevention (CDC) and Google Trends, and private partners such as Meta and Change Healthcare. To learn more about the Meta partnership, check out this article. It is built and maintained by the Carnegie Mellon University Delphi Research Group.
This package is designed to streamline the downloading and usage of
data from the Delphi Epidata API. It provides a simple R interface to
the API, including functions for downloading data, parsing the results,
and converting the data into a tidy format. The package can also fetch
the full historical record of a signal, including corrections and
updates, which is particularly useful for accurately backtesting
forecasting models. It can also fetch accessory data associated with a
signal, such as source-specific metadata, via
epidata_aux(). We also provide packages for downstream data
processing (epiprocess) and
modeling (epipredict).
# Install the CRAN version
pak::pkg_install("epidatr")
# Install the development version from the GitHub dev branch
pak::pkg_install("cmu-delphi/epidatr@dev")Our CRAN listing is here.
The Delphi API requires a (free) API key for full functionality. To
generate your key, register for a pseudo-anonymous account here
and see more discussion on the general
API website. The epidatr client will automatically look
for this key in the environment variable
DELPHI_EPIDATA_KEY. We recommend storing your key in your
.Renviron file, which R will read by default.
Note that for the time being, any private endpoints (i.e. those
prefixed with pvt) will require a separate key that needs
to be passed as an argument.
To get started with epidatr, see
vignette("epidatr") or the Getting
Started guide.
library(epidatr)
# Discover what a source offers: signals, geo types, and date ranges
meta <- epidata_meta(source = "nssp")
meta$signals
#> [1] "pct_ed_visits_ari" "pct_ed_visits_combined"
#> [3] "pct_ed_visits_covid" "pct_ed_visits_influenza"
#> [5] "pct_ed_visits_rsv" "smoothed_pct_ed_visits_combined"
#> [7] "smoothed_pct_ed_visits_covid" "smoothed_pct_ed_visits_influenza"
#> [9] "smoothed_pct_ed_visits_rsv"
# Fetch the latest snapshot of NSSP influenza ED visit percentages by state
flu <- epidata_snapshot(
source = "nssp",
signals = "pct_ed_visits_influenza",
geo_type = "state"
)
flu
#> # A tibble: 10,506 × 7
#> signal report_time geo_type geo_value fill_method reference_time value
#> <chr> <date> <chr> <chr> <chr> <date> <dbl>
#> 1 pct_ed_visit… 2026-06-26 state ak source 2022-10-01 0.140
#> 2 pct_ed_visit… 2026-06-26 state ak source 2022-10-08 0.240
#> 3 pct_ed_visit… 2026-06-26 state ak source 2022-10-15 0.320
#> 4 pct_ed_visit… 2026-06-26 state ak source 2022-10-22 0.760
#> 5 pct_ed_visit… 2026-06-26 state ak source 2022-10-29 1.16
#> 6 pct_ed_visit… 2026-06-26 state ak source 2022-11-05 1.94
#> 7 pct_ed_visit… 2026-06-26 state ak source 2022-11-12 3.73
#> 8 pct_ed_visit… 2026-06-26 state ak source 2022-11-19 6.82
#> 9 pct_ed_visit… 2026-06-26 state ak source 2022-11-26 8.67
#> 10 pct_ed_visit… 2026-06-26 state ak source 2022-12-03 9.85
#> # ℹ 10,496 more rowsThis is just a glimpse of what epidatr can do. See the
Articles
for walkthroughs of specific tasks (finding signals, understanding
versioned data, migrating from pub_covidcast()), and the Reference for
the full list of functions and their arguments.
The Delphi Epidata API has three generations of endpoints, and this package has client functions for all of them:
epidata_snapshot(),
epidata_archive(), and epidata_meta(). Start
here; sources are moving to v5 one at a time.pub_covidcast(). Still
carries the sources that have not moved to v5 yet.pub_*
functions (e.g. pub_fluview(), pub_gft()), one
per dataset. Most of these datasets are static or no longer updated;
they remain available for historical work.If you have existing pub_covidcast() code, see
vignette("migration-guide") for the argument and column
mapping to the v5 functions.
If you are migrating existing workflows, there are two transitions to keep in mind:
covidcast package to epidatr. The
standalone covidcast
package is deprecated and superseded by epidatr, which
is a complete rewrite offering better speed, reliability, and broader
endpoint support.epidatr,
pub_covidcast() and other V3/V4 endpoints are being
deprecated as of October 2026. See the migration
guide (or vignette("migration-guide")). New code should
use the current V5 functions (epidata_snapshot(),
epidata_archive(), and epidata_meta()),
reserving pub_covidcast() only for sources that have not
yet transitioned.You should consider subscribing to the API mailing list to be notified of package updates, new data sources, corrections, and more.
If you use epidatr or data from the Delphi Epidata API
in your work, please cite the package using citation("epidatr").
If you use data that originated from the COVIDcast project (whether
accessed via V5 endpoints or pub_covidcast()), please
include the COVIDcast
citation as well.
Certain data sources have specific attribution and licensing terms. See the Epidata data licensing documentation and the COVIDcast licensing documentation for information about citing specific datasets.
Warning: If you use data from the Epidata API to power a product, dashboard, app, or other service, please download the data you need and store it centrally rather than making API requests for every user. Our server resources are limited and cannot support high-volume interactive use.
See also the Terms of Use, noting that the data is a research product and not warranted for a particular purpose.