The Iowa Department of Public Health has erroneously recorded thousands of positive COVID-19 test results, distorting reported case numbers and positivity rates.

Rob Ramaekers, the lead epidemiologist for the department’s Surveillance Unit, acknowledged in an August 14 email that Iowa’s coronavirus website has recorded some recent cases as occurring weeks or months in the past. According to Ramaekers, state officials are aware of the problem and working on a fix.

The backdating means that publicly available numbers underestimate the positivity rate for COVID-19 tests conducted over the past two weeks, a key metric for measuring community spread.