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On May 9, 2020, 109 days after the first known case of COVID-19 in the United States, the Centers for Disease Control and Prevention launched its first national and state-level release of COVID-19 testing data from public, hospital, and commercial laboratories.

The COVID Tracking Project at The Atlantic has released a white paper collecting the results of our in-depth review of the differences between the CDC’s case, death, and testing data compared to the corresponding data publicly reported by the states and the District of Columbia.

Download: Assessment of the CDC’s New COVID-19 Data Reporting, v1.0 (May 18, 2020)

This research is licensed CC-BY 4.0. Please attribute it to “The COVID Tracking Project at The Atlantic.” You can contact us anytime at

Highlights from the report:

  • The new case and death counts from the CDC show a high degree of concordance with official state-reported data. If these numbers continue to be regularly reported and aligned, The COVID Tracking Project will begin using the CDC’s case and death counts in our public reporting and API.
  • The new testing data from the CDC, however, differs from official testing data reported by state health departments. In 29 states, the raw numbers fall within 10% of each other, while in 13 states, the data diverges by 25% or more. Adjusting for different reporting methodologies does not fully explain these differences.
  • Small variations in these datasets are to be expected, but large gaps are cause for concern. For many states, the CDC publishes higher testing numbers than the states themselves report, which raises questions about the structure and integrity of both state and federal data reporting.
  • Another point of contrast between the CDC’s new reporting and the official state data compiled by The COVID Tracking Project is that the CDC has not released historical, state-level testing data for the first three months of the outbreak. Until we can reconcile the CDC’s new data with the state-reported data that makes up our historical dataset, the new data is of limited use to disease modelers and other COVID-19 data users.
  • As part of our accountability mission, The COVID Tracking Project team will do everything we can to understand and close the gaps between the state and federal data. That work begins with this assessment, and will continue as we integrate the CDC data into our dataset and data API.