An Open Repository of Real-Time COVID-19 Indicators.




The COVID-19 pandemic presented enormous data challenges inthe United States. Policy makers, epidemiological modelers, andhealth researchers all require up-to-date data on the pandemicand relevant public behavior, ideally at fine spatial and temporalresolution. The COVIDcast API is our attempt to fill this need:Operational since April 2020, it provides open access to bothtraditional public health surveillance signals (cases, deaths, andhospitalizations) and many auxiliary indicators of COVID-19 ac-tivity, such as signals extracted from deidentified medical claimsdata, massive online surveys, cell phone mobility data, and in-ternet search trends. These are available at a fine geographicresolution (mostly at the county level) and are updated daily. TheCOVIDcast API also tracks all revisions to historical data, allowingmodelers to account for the frequent revisions and backfill that arecommon for many public health data sources. All of the data areavailable in a common format through the API and accompanyingR and Python software packages. This paper describes the datasources and signals, and provides examples demonstrating thatthe auxiliary signals in the COVIDcast API present informationrelevant to tracking COVID activity, augmenting traditional publichealth reporting and empowering research and decision-making.

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