Minnesota hopes to do massive-scale coronavirus testing of residents 18 to 35, but the Department of Health first needs to determine the best way to conduct those tests and how accurate they will be.
That was the message from state health leaders Wednesday in response to questions about plans floated this week by Gov. Tim Walz and by Dr. Deborah Birx of the White House coronavirus task force, who visited Minnesota on Sunday.
Both said widespread testing of the 18-35 age group, whether or not they have symptoms, could help the state contain the growing pandemic. Coronavirus cases have been rising in younger adults since summer, and while relatively few have died, health officials fear they are spreading COVID-19 to more vulnerable members of the community.
“There are a lot of people circulating in the community who have been exposed, don’t know they are positive and are spreading the virus unknowingly,” state health commissioner Jan Malcolm said.
Minnesota reported 1,916 new infections and 19 more COVID-19 deaths Wednesday and saw its test positivity rate in double digits for the second day in a row, which hadn’t happened since May.
The newly reported deaths, all people ages 70-94, bring the pandemic’s toll to 2,387. Sixteen of them lived in long-term care and three in private homes.
Meanwhile, the state’s hospitalizations for COVID-19 climbed to 680 patients, including 166 in critical condition, as of Tuesday afternoon. That’s almost 100 more patients than this time last week.
NEW LAB, MORE TESTS
With a new saliva-testing lab opening last week in Oakdale, Minnesota is closer to being able to process 50,000 diagnostic coronavirus tests each day. But tests using nasal swabs and saliva samples that search for virus DNA still need to be processed in a laboratory and results typically take at least a day.
To perform massive-scale testing, health officials likely would need to use rapid tests that look for antigens in the blood that signal the immune system is responding to a coronavirus infection. Antigen tests can return results in as little as 15 minutes but are not as accurate as diagnostic tests.
Malcolm said Wednesday that health officials were in the early stages of working out logistics for how to use antigen tests for large-scale coronavirus screening, but a lot depends on their reliability.
The governor, Malcolm said, “wants us to figure out these logistics as fast as we can.”
Abbott Laboratories, which manufactures the rapid tests, has said their accuracy is between 93 percent and 98 percent, although critics have challenged that claim.
Since March, Minnesota has screened 2.7 million samples from 1.8 million patients with diagnostic tests. Only about 26,920 antigen tests have been completed and reported to the health department, with the rapid tests most commonly being used in long-term care facilities.
Health officials note that any coronavirus test represents a moment in time and that a person can develop an infection with hours or days of testing negative. Minnesota currently classifies any coronavirus case found with an antigen test as a probable case, while those found with diagnostic tests are referred to as confirmed cases.
Just 112 of the 1,916 new infections the health department announced Wednesday were from antigen tests.
Test results reported Wednesday equate to a one-day positivity rate over 12 percent.
Health officials are quick to note that daily positivity rates don’t say much about the severity of the state’s outbreak. A more stable measure of recent infections, the seven-day rolling average for positive tests, stands at 7.2 percent, which is significantly higher than the 5 percent threshold that suggests the virus is spreading uncontrollably.
Minnesota has diagnosed 139,444 cases of COVID-19 since the virus arrived in the state. Of those, 123,529 people have recovered enough that they no longer need to be isolated.
