Dates of more than 30K Ohio COVID-19 cases changed

Ohio made a database tweak that changed records for more than 30,000 COVID-19 cases – about 3% of the state's cumulative total – on Wednesday.

The change wasn't visible on the state's dashboard but could be seen in a comparison of the spreadsheet made available to download each day.

The one-time change didn't affect the number of cases – everyone who was recorded as a case before Wednesday remains a case. But for thousands, the recorded illness "onset date" changed.

There are two dates associated with cases: the date a case is reported publicly by the Ohio Department of Health and the "onset date" of when someone first felt ill, which is recorded in the case record in the Ohio Disease Reporting System.

For example, there were 4,600 new COVID-19 cases reported Wednesday, but only 35 of those had an "onset date" of Wednesday.

But if there isn't a date entered, which is the case when asymptomatic people test positive for COVID-19, the system defaults to another date, typically the day the diagnostic test was taken.

That's how the system works for a number of diseases reported to the state. COVID-19 is different because the state is requiring all negative results to be reported in addition to positive tests.

So in some 33,000 instances over the past year where someone had both positive and negative results on their record, the system used the date of a negative test date instead of a positive one, according to the Ohio Department of Health.

The Ohio Department of Health updated the system to only use the positive test date on June 14 going forward. On Wednesday, it updated all the cases with dates before June 14.

"These changes do not impact the trends we have been seeing during the course of the pandemic, or the trends visible on the COVID-19 dashboard – they simply ensure the most accurate data possible is displayed," department spokesperson Alicia Shoults said.

The largest net shift in dates happened in December and January, during the largest coronavirus surge yet in Ohio.

Jackie Borchardt is the bureau chief for the USA TODAY Network Ohio Bureau, which serves news organizations across Ohio.

LIZ DUFOUR/THE ENQUIRER The change didn’t affect the number of COVID-19 cases reported so far, just the date of when about 3% were diagnosed.