JEFFERSON CITY, Mo. — The percentage of coronavirus tests coming back positive has increased 7.3% over the past seven days in Missouri, the number reported as state officials decided to clarify their testing metrics on May 23.
Until now, staff working on the case count had combined virus testing with antibody testing. Virus testing, or PCR testing, shows who currently has the virus. Antibody testing, or Serology testing, shows who has had it and developed antibodies. Some people have received both tests.
This combined number gave a bigger number since it was the total number of tests. However, this number was then used to divide the number of positive cases taken from only virus testing. Ultimately, muddling together total testing numbers with the positive cases from only one type of testing created a lower percentage of positive cases than really exist.
The state is now using the total number of people who have been tested instead of the total number of tests, which makes for a smaller, more accurate number when finding a percentage of the population who has contracted the coronavirus.
The Missouri COVID-19 dashboard now reflects the new number of positive cases out of the population in addition to separate tabs for both PCR and Serology testing numbers.
“As we continue to learn more about this virus and new tests emerge, we will continue providing better data with greater clarity and transparency to help Missourians make the best decisions for their health care possible,” Dr. Randall Williams, director of DHSS, said in a statement.
Williams ultimately blamed the misleading testing numbers on direction from the CDC, saying his staff had been instructed to combine data.
However, he did not specify exactly what the CDC told the state to do. It’s unclear if the state was directed to use this data in determining percentage of positive tests. However, the department does acknowledge that the percent of positive tests will increase with the change.
“These changes will increase the rate of positive cases as reported through the dashboard,” according to the DHSS.
DHSS representative Lisa Cox said in a statement that, “as per specific instructions given during conversations with the CDC to report combined testing data, staff subsequently did just that.”