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The Oregon Health Authority today announced a major change in the way it will report COVID-19 test results.
Until now, the state has reported the number of unique individuals tested (that number is nearly 1 million). The state refers to that as a "person-based" count.
That reporting method has consistently ranked Oregon at the bottom nationally in per capita testing.
A KGW-TV news story this week identified a big discrepancy between the number of tests conducted and the number reported by the state.
Today, Dr. Melissa Sutton, an OHA physician involved in the state's testing regime, explained that difference: The higher number—a "test-based" count— captures subjects who have been tested more than once.
So, for instance, if Jane Doe were tested in March and then three more times subsequently, OHA would count that as one test—noting the first one but not including the subsequent three tests. Jane Doe would not be included in the state's count again unless she tested positive. The state will no longer count tests in this fashion.
"Our testing methodology is significantly undercounting the number of tests performed," Sutton said.
When OHA instead reports the absolute number of tests performed, the number reported will be significantly higher—and will place the state in the middle of the pack nationally in tests per capita rather than nearly last.
"Based on the number of tests performed, we are not at the bottom," Sutton said. "We rank 30th per rate of tests performed."
Sutton explained that the U.S. Centers for Disease Control and Prevention, which is responsible for compiling national health statistics, allows states to count either way—person- or test-based—but Oregon will make a change to better reflect what is happening.
Now the state will shift to a "test-based" count that would say Jane Doe has been tested four times and would add any new tests she takes to the total, even if the results are negative.
The effect of that shift in methodology is significant, more than doubling the reported tests per week.
Here's how the numbers look using the two methods:
Changing the methodology will also change another important measurement of COVID-19's impact on the state, the rate of positivity, or the percentage of tests that come back positive for the virus.
The effect of changing from counting the number of unique individuals tested to the number of tests performed will greatly increase the denominator of the equation (positive results divided by the number of tests), lowering the reported rate of positivity.
Here's what the change looks like:
Even at the lower rate of positivity—about 7% rather than above 12% in the person-based method—Oregon is well above the 5% guideline that federal officials say marks a danger zone for community spread.
As officials explained the new way of presenting testing results today, OHA director Patrick Allen disclosed the case count today hit 1,306, yet another single-day record. COVID-19 hospitalizations also reached an all-time high.
Allen urged Oregonians to observe Gov. Kate Brown's executive orders, which include a two-week shutdown; a limit on home gatherings to no more than six people; and orders to wear masks, wash hands and maintain social distance of 6 feet or more.
"We are entering a critical stage of the pandemic," Allen said. "People are dying at a faster rate and severely ill patients will swamp our hospitals."