“They were releasing and even highlighting a lot of studies that were pretty correlational and not very convincing,” said Harris.

Jay Varma, who was previously a health advisor for New York City, says clear information on the effectiveness of different mitigation measures would have been especially helpful — but was lacking. “What if I do this ventilation technique? What if I try this masking approach? What if I do this distance?” he said.

In other instances, the CDC simply mischaracterized research evidence.

In March 2021, the agency announced an important shift to its guidance: it was relaxing recommended distancing in schools from six feet to three feet. In an accompanying scientific brief, it claimed that COVID transmission in schools was low “even when student physical distancing is less than 6 feet.” One piece of evidence was a Florida study that purportedly showed that COVID spread was higher when fewer students were learning in person.

In fact, the study showed exactly the opposite, undermining the new guidance. After Chalkbeat inquired about this discrepancy, the CDC quietly corrected its brief but did not change its characterization of the overall research.