The data sets have one known major difference: Some states report the total number of people tested, while the CDC reports every test, even if a single person is tested more than once. A spokesperson for Indiana’s public health department pointed to this difference to explain the state’s test gap. But our analysis suggests this—or any other methodological factor—does not fully explain the widespread discrepancies. Caitlin Rivers, an epidemiologist at the Johns Hopkins University Center for Health Security, told us that one possible explanation is that the CDC could be overreporting testing totals in some states if it is including antibody-test results, which don’t track real-time infections, and underreporting in other states because of delays in paperwork. But the differences seem to be so widespread that they are unlikely to arise from a single discrepancy in how certain kinds of tests are reported. At their current rate of growth, Florida’s state-reported testing numbers would not match the CDC’s current totals for another two weeks.
“This is more evidence of the dysfunction of the CDC,” Jha said. “There is not supposed to be a lot of daylight between the CDC and the states.” Jha has previously criticized the CDC for being “inexplicably absent” during the coronavirus pandemic.
Some of the mismatch between states and the CDC could be explained by the federal government’s unusual manner of collecting testing data. Generally, disease-surveillance data flow from local public-health departments to state governments, and then on to the federal government. But in April, Vice President Mike Pence asked hospitals to start reporting their COVID-19 testing data directly to the federal government. In an email, a CDC spokesperson confirmed that the new website reflected test data from more sources than just states, saying it came from hospitals, private medical-testing companies, and state and local public-health labs.
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The data that Pence requested fed into a piece of software called HHS Protect, which was meant to serve as a clearinghouse of coronavirus data for the Trump administration, according to a spokesperson for the Department of Health and Human Services. HHS Protect was developed by the defense contractor Palantir. The company declined to comment on the record.
It’s unclear exactly when the CDC site first appeared. A CDC spokesperson told us that it went live on May 7, but the first Internet Archive cache of the page is dated May 9. The CDC did not announce the existence of the page in any statement, social-media post, or press conference.
In many of the counts the CDC did provide over the past several months, it missed the large majority of tests. In early May, the CDC reported that only about half a million tests had been conducted in the U.S. But the COVID Tracking Project had tallied the results of more than 7.5 million tests reported by states by then. In late April, the White House used the COVID Tracking Project’s data in a major report on national testing strategy. It cited the data again earlier this week in a press conference.
The CDC should provide the country with a single, trustworthy data source on the state of COVID-19 testing. But the fact that its data are still in such disagreement with the state-reported totals means that the CDC’s latest efforts are not of much use to politicians and the public. For now, the agency that should be a respected source of truth in this crisis is only adding to the national confusion.