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Dryad

Annotations on COVID-19 state data definitions as of March 7, 2021

Data files

Feb 24, 2022 version files 763.05 KB

Abstract

The COVID Tracking Project was a volunteer organization launched from The Atlantic and dedicated to collecting and publishing the data required to understand the COVID-19 outbreak in the United States. Our dataset was in use by national and local news organizations across the United States and by research projects and agencies worldwide.

In the US, health data infrastructure has always been siloed. Fifty-six states and territories maintain pipelines to collect infectious disease data, each built differently and subject to different limitations. The unique constraints of these uncoordinated state data systems, combined with an absence of federal guidance on how states should report public data, created a big problem when it came to assembling a national picture of COVID-19’s spread in the US: Each state has made different choices about which metrics to report and how to define them—or has even had its hand forced by technical limitations.

Those decisions have affected both The COVID Tracking Project’s data, assembled from states’ public data releases, and still affect the CDC’s data, which mostly comes from submissions from state and territorial health departments. And they have had real consequences for the numbers: A state’s data definitions might be the difference between the state appearing to have 5% versus 20% test positivity, between labeling a COVID-19 case as active versus recovered, or between counting or not counting large numbers of COVID-19 cases and deaths at all.

Because state definitions affect the data we collect, COVID Tracking Project researchers have needed to maintain structured, detailed records on how states define all the testing and outcomes data points we capture in our API (and a few we don’t). Internally, we call this constantly evolving body of knowledge “annotations.” Today, we are for the first time publishing our complete collection of annotations.