Last week, after reporting from the Guardian on mortality rates among children, the CDC corrected a “coding logic error” that had inadvertently added more than 72,000 Covid deaths of all ages to the data tracker, one of the most publicly accessible sources for Covid data. The Guardian reports: The agency briefly noted the change in a footnote, although the note did not explain how the error occurred or how long it was in effect. A total of 72,277 deaths in all age groups reported across 26 states were removed from the tracker “because CDC’s algorithm was accidentally counting deaths that were not Covid-19-related,” Jasmine Reed, a spokesperson for the agency, told the Guardian. The problem stemmed from two questions the CDC asks of states and jurisdictions when they report fatalities, according to a source familiar with the issue.
One data field asks if a person died “from illness/complications of illness,” and the field next to this asks for the date of death. When the answer is yes, then the date of death should be provided. But a problem apparently arose if a respondent included the date of death in this field even when the answer was “no” or “unknown.” The CDC’s system assumed that if a date was provided, then the “no” or “unknown” answer was an error, and the system switched the answer to “yes.” This resulted in an overcount of deaths due to Covid in the demographic breakdown, and the error, once discovered, was corrected last week. The CDC did not answer a question on how long the coding error was in effect.
“Working with near real-time data in an emergency is critical to guide decision-making, but may also mean we often have incomplete information when data are first reported,” said Reed. The death counts in the data tracker are “real-time and subject to change,” Reed noted, while numbers from the National Center for Health Statistics, a center within the CDC, are “the most complete source of death data,” despite lags in reporting, because the process includes a review of death certificates.
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