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What the Minnesota Health Department hopes to learn from COVID-19 blood tests

The department recently requested $1.975 million for five studies to help determine how COVID-19 has spread in Minnesota.

COVID-19 blood tests are useful on a broader scale to help answer questions about what share of the population has been exposed to the disease, as well as help us understand what interventions might slow its spread.
REUTERS/Benoit Tessier

About a month and a half ago, Minnesota Gov. Tim Walz announced a plan to test as many as 20,000 Minnesotans per day for COVID-19.

In the weeks since, the number of molecular tests — tests aimed at detecting if someone is currently infected with COVID-19 — have increased fairly quickly, from about 2,000 per day to upwards of 10,000 some days.

Details on the other part of the testing plan — serology, or blood tests that detect past infection — have been slower to emerge.

That’s partly because the utility of these tests is limited in some ways: for now, experts can’t say whether people who come through COVID-19 develop antibodies sufficient to ward off future infection, or if they do, how long those would last. 

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For that reason, they say, it’s not currently helpful on an individual level to know whether or not you’ve had COVID-19: it doesn’t give you a pass to go into crowds or grocery shop without a mask without fear of future infection or infecting others. But COVID-19 blood tests are useful on a broader scale to help answer questions about what share of the population has been exposed to the disease, as well as help us understand what interventions might slow its spread.

Among the expenditures Gov. Tim Walz’s administration has listed will come from the nearly $1.9 billion in federal dollars sent to the state for COVID-19 response is $1.975 million for five serological studies to be done jointly by the Minnesota Department of Health and the University of Minnesota’s School of Public Health, designed to help answer those questions.


As part of its request to the state COVID-19 fund, the Minnesota Department of Health proposed a survey of communities across Minnesota.

The survey would use the Centers for Disease Control’s Community Assessment for Public Health Emergency Response (CASPER) technique, designed to quickly collect information from households that can help officials plan and respond to emergencies such as by helping officials understand how to distribute resources, respond to community needs and create public health messaging.

“It is a way to assess a community after an event. Typically it’s something like a flood, or a hurricane, and they can go in and rapidly do a community assessment,” said Dr. Ruth Lynfield, the state epidemiologist.

While it’s often used for natural disasters, the technique has also been used to get a handle on Zika virus and the H1N1 flu strain in the past.

For the purposes of Minnesota’s COVID-19 study, this involves a survey of 210 households, chosen by random sample, in seven different areas of the state. Households will be interviewed about symptoms and exposures as well as a blood test for COVID-19 if respondents are interested.

The study would be done in the summer, fall and spring, with the goal of getting started before the fall. The seven communities have not yet been selected, but Lynfield says she hopes to have news on that in a few weeks.

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Another antibody study that was part of MDH’s budget request involves adding a serology component to an ongoing study of 344 Minnesotans that’s aimed at understanding the effects of COVID-19 on physical health, mental health, economic security and social dynamics.

Scanning blood banks

Starting this week is a study that involves scanning leftover blood samples held by Memorial Blood Banks in the Twin Cities metro area and in Northern Minnesota for COVID-19 antibodies.

The samples will be de-identified, meaning the name of the donor won’t be attached to the samples, but MDH is hoping to have the donor’s county of residence or another geographic indicator that shows where the donor is from.

A lab technician taking a blood sample for COVID-19 serological test on a woman.
REUTERS/Benoit Tessier
A lab technician taking a blood sample for COVID-19 serological test on a woman.
Like the community survey, the blood bank tests will be completed over the summer, fall and spring.

Grocery store and health care workers

To better understand the exposure of Minnesotans who are working on the front lines of the COVID-19 pandemic, MDH will work with the University of Minnesota to survey grocery store and health care workers, including antibody tests.

As society began to shut down mid-March after COVID-19 came to Minnesota, grocery stores were one of the few things that remained open, putting workers at potentially high risk of exposure to the virus, said Craig Hedberg, a University of Minnesota professor and interim division head of the School of Public Health’s Environmental Health Sciences, who is doing the study.

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That makes studying their exposure to the virus useful for two reasons:

“If grocery store workers were becoming infected as a result of exposure in their workplace setting, that that would be an important measure of community spread in those areas,” Hedberg said. “We could also sort of learn from the experience of grocery store workers as we begin to think more about exposure in other settings as we start opening up more.”

It could also help researchers better understand which interventions — whether it’s plexiglass, required masks or metered entry — help reduce the chance of transmitting COVID-19, which could inform efforts to safely reopen other types of businesses.

“The point isn’t to call out any specific grocery stores as being good or bad , we’re just trying to get a sense to see if we have evidence of infection among grocery store workers, look and see whether there’s anything we can learn about the controls that were in place in those settings. and if there’s any correlation,” Hedberg said.

Another study would test the antibodies of 500 health care workers in Minnesota every three months for a year in an effort to understand the exposure risk of those who are most on the front lines of the COVID-19 pandemic.

“We think that through this variety of studies that we will get some insight into different communities in Minnesota and to how they may have been exposed to this virus,” Lynfield said in a press briefing last month.

More efforts underway

These efforts aren’t the only ones seeking to better understand how COVID-19 is affecting Minnesotans by studying their antibodies. Researchers at the University of Minnesota and the Mayo Clinic are both working to better understand COVID-19 antibodies.

On Thursday, the Mayo Clinic announced a test initiative with corporate partners that could help determine how effective a person’s antibodies are at neutralizing the coronavirus.

“We’re learning more and more every day about this virus. We will know a lot more a month from now than we know today, and when I look at what we know today compared to what we knew a couple months ago, we have really learned a lot,” Lynfield said. “The more we learn, the more informed the decisionmakers can be.”