The COVID positivity rate, which Johnson County health officials say is too high for schools to safely open, includes people who tested positive and negative, according to county officials. At this time, it’s unknown whether any of those who tested positive and negative could be considered ‘false positives.’
The Sentinel asked county officials over the weekend why, on Friday, the total number of positive cases (6,930) and negative cases (86,730) exceeded the total number reported for individuals tested (92,066) by a measure of 1,594. In response, Director of Epidemiology Elizabeth Holzschuh wrote,” The ‘individuals tested’ represents the number of Johnson County residents who have been tested. A person who has tested both positive and negative is represented in both the ‘positives’ and negatives’ but only once in the ‘individuals tested.”
That response prompted these follow-up questions, sent to county health officers, commissioners, and public relations staff:
- How many people tested positive only?
- Of those included as both positive and negative, how many people tested positive and then negative?
- Of those included as both positive and negative, how many people initially tested negative and then positive?
- Of those who tested both positive and negative, how many tested negative within 24 hours…48 hours…and more than 48 hours?
- We’ll need the weekly numbers (as of each Monday) for those counted as positive who subsequently tested negative.
- If the time span between tests is less than 24 hours, that could indicate an initial false positive…so why count it as a positive and increase the positivity rate?
- Why were people retested who initially tested positive?
- Is it possible that some of people who tested positive and negative are false positives? And if not, how does the county know that?
- Could the number of reported positives include people who were told they tested positive by one facility and subsequently went to another facility to be tested again (maybe to get confirmation of their initial diagnosis)…and again tested positive…resulting in two positive results in the county? Put differently, does the county have data confirming that the 6,930 positive cases are from 6,930 unique individuals?
Dr. Samni Areola wrote back, saying “no one is counted twice for positive tests. And no one is counted twice for negative tests. However, the same individual could have tested negative before testing positive in which case it will show up in both counts.
We do not recommend that people test again after they have tested positive. However, some do. They are not counted afterwards.”
Areola’s response could indicate that the answer to question #9 above is that no individuals are counted twice as positive, regardless of whether tested by the county or elsewhere. But his statement preceded the submission of question #9 and no response has been provided since sending it.
Dr. Areola did say that Johnson County does not include any ‘probable’ COVID cases as positive. The State of Kansas does, however, include an unknown number of ‘probable’ cases in statewide totals, but won’t say how many or in which counties.
Areola said responses to questions #1 through #8 will be provided “as time permits.”
False positives, skewed testing sample
Just today, the National Football League announced that all 77 false-positive COVID-19 tests from Saturday came back negative upon retesting. The problem was attributed to “an isolated contamination” in the New Jersey lab that processed the test.
Dr. Areola says, “it is inaccurate to say that positivity rate is being inflated” because the county is including everyone who tested positive, but the county hasn’t said whether anyone tested negative within 24 hours of testing positive. Counting people as positive who also tested negative may be standard procedure for gathering health statistics, but the public has a right to know how many people reported as positive then tested negative within a short period of time; especially since the positivity rate reported by Johnson County is determining whether students can return to school.
Last week, Johnson County pediatrician Dr. Christine White told the Blue Valley school board that the county’s COVID positivity rate is artificially high because “the data is obtained from a skewed sample.” White says the vast majority of people tested in Johnson County already have symptoms or have a known exposure to COVID. Her statement was shared with Johnson County officials last Thursday and the county has not commented on it.
White said Shawnee Mission Medical Center has tested 7,500 asymptomatic pre-op patients over the last three months and found just 0.5% (half of one percent) tested positive for the virus. She urged the district not to use the Johnson County’s skewed COVID positivity rate to decide whether it’s safe to open schools.