FARGO — Gov. Doug Burgum's Democratic challenger Shelley Lenz says North Dakota is skewing the rate of positive coronavirus cases by using a method that emphasizes negative test results — resulting in a much lower reported infection rate.
North Dakota's positive rate among those tested for coronavirus infection over 14 days averaged 5.7% Tuesday, July 21, and has ranged from 4.8% on July 10 to 8.7% on July 14 , according to Johns Hopkins University.
Those infection rates are higher than those reported by the North Dakota Department of Health, which reported a daily positivity rate of 2.2% for test results released on Tuesday, and figures resulting in a cumulative positive rate of 3.77%.
In recent weeks, North Dakota's positive rate has consistently fallen in the 3% range, while the Johns Hopkins method has consistently been higher.
The positivity rate is a key indicator in guiding decisions, including whether to allow businesses to reopen and at what level, and will be closely watched as school officials decide how to handle classes in the fall.
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The World Health Organization recommends maintaining a positivity rate of no more than 5%, a level it says ensures that testing is adequate to keep infections from spiraling out of control.
North Dakota tracks positive cases as a percentage of total tests, instead of as a percentage of unique individuals, because serial testing of vulnerable populations means it is common to test people more than once, said Kirby Kruger, the state's director of disease control at the North Dakota Department of Health.
"People who have been tested and test negative are still considered to be part of the susceptible population," he said. "With over 137,000 unique tests completed, we've now tested nearly one in five North Dakotans. As that number continues to grow, the percentage of those previously untested will continue to shrink."
Counting only unique tests in the positivity rate "will increasingly ignore a huge segment of the population and not accurately reflect community spread," Kruger said.
"The most important thing is we track it consistently so we can see important trends," he said.
The method of calculating the infection rate by Johns Hopkins and most other states divides the number of positives by the number of unique individuals who have been tested, while North Dakota apparently divides the number of positive cases by the total number of individuals who have been tested, resulting in a lower rate, said Bill Gillerstein, a Fargo resident who tracks the rate.
The difference stems from serial testing of those who are at high risk of infection, who typically have multiple negative tests and a single positive test, he said. North Dakota's method effectively divides positive cases by a larger number of negative results.
"That's why the state's numbers are so low," he said.
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Lenz, the Democratic nominee for governor, who is also tracking the state's reporting of COVID-19 infections, said North Dakota's method is misleading.
"We're not at 2%, we're actually at 5%, which makes us a hotspot," said Lenz, who is a veterinarian in Dickinson.
The understated infection rate comes at a critical time, as school officials around the state are deciding how to resume classes this fall, either in-person, via distance education or through a hybrid of the two, she said.
"We're making some really hard decisions right now," Lenz said. "Clear scientific communication is critical for the general public in understanding what's going on."
Despite state figures, "2% is not what's happening," she said.
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The average person is not capable of calculating the more accurate rate, which would involve logging daily testing figures reported for their county, then calculating a positive rate, Lenz said.
Yet parents, business owners and school officials around North Dakota are relying on figures reported by the state, she said.
"They're flying blind," Lenz said. "We need to know what is true" in order to make "life or death decisions."
"They're either incompetent or something more nefarious," she added, referring to what she said is the misleading picture drawn by state reports.
"It is a betrayal of public trust," Lenz said.
As of Tuesday, the positive testing rate ranged from a low of 0.8% for Connecticut and Vermont to a high of 23.4% for Arizona. South Dakota had a positive rate of 5.8%, Montana, 3.8% and Minnesota, 4.4%, according to Johns Hopkins.
Gillerstein, who is 66, said he is closely tracking the positive rate because he has been hospitalized multiple times for pneumonia. Because he considers himself at high risk for COVID-19 complications, he wants accurate information to guide his decisions.
North Dakota once computed the positive rate the same way Johns Hopkins and most other academic centers and states do, but switched its method with the results posted around May 15, he said.
"They were doing it correctly," Gillerstein said. "The only thing I can come up with is they want to have low numbers so they look really good," he said, referring to North Dakota's altered method for reporting positive testing rates.
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"This wasn't political for me why I started," he said, although he acknowledges relaying his concerns to Lenz and Sen. Tim Mathern, D-Fargo. "It was only a guy wanting information for my own personal use."
North Dakota apparently is using the same method for calculating the positive test result as Florida, Gillerstein said, which has been criticized for skewing its results, suggesting a lower infection rate.
The Florida method counts positive results once, but counts negative results more than once, according to a news report by the South Florida SunSentinel .
Florida's method also was criticized by Dr. Jason Salemi, an epidemiologist with the University of South Florida, who was interviewed July 17 on CNN.
"It's valid, but it's hugely misleading," Salemi said of Florida's method of reporting positive test rates. Salemi said Florida would better serve the public by reporting positive rates more completely.
"At a minimum the (Florida) Department of Health should be reporting both — at the test level and at the person level," he said.
North Dakota has denied requests by Lenz and Gillerstein to release the raw data behind the positive test rates for individual counties, citing health privacy laws. Releasing the data for sparsely populated rural counties risks enabling people to identify individuals, according to the state.
But Lenz notes that the state already releases testing figures for each county and does not believe privacy is a valid reason for withholding the information. Gillerstein also is skeptical.
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"That's ridiculous to me," he said.