MDH says positivity rate accurate despite about 25,000 backlogged tests added Wednesday

Every day, the Minnesota Department of Health shares how COVID-19 is spreading across the state.

“We are announcing an additional 567 laboratory-confirmed cases, bringing our new total to 66,618,” said Commissioner Jan Malcolm on Wednesday.

The rate of positive cases is tracked not only by Minnesota health officials but those across the country as they make policy decisions, including for travel.

“You want to see that number be at the 5% threshold or lower because that lets you know the virus is being fairly well contained in the community,” said KSTP Medical Expert Dr. Archelle Georgiou.

Minnesota has been right around a 5% positivity rate since June. It’s calculated by comparing the number of positive cases to the overall number of tests completed.

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Commissioner Malcolm announced on Wednesday they just added about 25,000 backlogged tests to the system, some dating back to April. MDH would not tell us how many of the backlogged tests were from April, May, June, July or August.

“The vast majority of those are negative test results that we have received for several labs,” said Malcolm.

MDH did not identify the labs that submitted the results.

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This is the third time MDH has added a backlog of tests to the state’s totals. The first occurred on April 29 and the second was on June 3.

According to MDH, it happens when they bring new labs on board.

“Certainly positive test results are the first priority when we get these news labs set up for reporting,” said Malcolm. “So we ask for those to be sent in first, which means we sometimes do get a backlog, in this case a significant backlog, of negative tests.”

We asked MDH if the positivity rate is still accurate.

Spokesperson Julie Bartkey told KSTP, “Yes, it is accurate…25,000 tests is a relatively low number when compared to the total COVID tests administered in Minnesota. We do not anticipate this will significantly impact positivity rates.”

She said they will look at the date of each of those tests and factor it into previous positivity rates.

“Mathematically, it doesn’t work that it’s accurate when you increase your denominator by 25,00 tests,” said Dr. Georgiou.

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For those who are looking for information about the severity of COVID-19 in Minnesota, she recommends looking at the hospitalization trends instead.

“The hospitalization data seems to be the purest, best number to go by right now,” she said. “For every hospitalization that occurs, there’s generally 10 people in the community that either have a mildly symptomatic case or a symptomatic case but not sick enough to be in the hospital. That gives us a pretty good view of what’s going on in the community so if the hospitalization rate is increasing you know that the community COVID rate is increasing as well.”