SIOUX FALLS, S.D. — Sanford Health is playing a crucial role in the push to track and curb the coronavirus. Its lab, housed in the health system’s massive headquarters building in Sioux Falls, is processing hundreds of tests every day.
How does the testing at Sanford work? Forum News Service went behind-the-scenes at the Sanford lab with Rochelle Odenbrett, senior executive director of Sanford Laboratories, to better explain the health system's testing.
Below is a summary of the testing process, from sample swab to test result.
How does a test sample get from person to lab?
Health care providers collect testing samples from people by inserting a long, thin nasopharyngeal swab up their nose. The swab is then placed in a solution — known as a viral transport medium — to keep the testing sample preserved while it is transported to the lab in Sioux Falls.
Couriers pick up the samples from across the Sanford health system as well as other clients of the lab, which means the lab is processing tests from North Dakota, South Dakota and Minnesota. If the distance is too far for the courier, samples are shipped via FedEx or UPS.
Does the lab prioritize tests?
Starting Friday, April 3, the lab is tweaking its priorities for tests, based on guidance from the U.S. Centers for Disease Control and Prevention:
Hospitalized patients and health care workers
Nursing homes, group homes and those over 65 years old
Outpatients including drive-through tests
The lab has only five people who are trained to process coronavirus tests, with one in training. Odenbrett said she hopes to double the staff size to better sustain the round-the-clock pace of testing.
The lab can process about 400 tests a day. About half of those are from South Dakota. The lab has a surge plan that would include sending tests to out-of-state labs. But so far that hasn’t been necessary, she said.
How is a test processed?
Lab workers add chemicals to the sample from the swab designed to kill the virus and dissolve its shell, releasing RNA molecules within the cell that the testing looks for to determine a positive result.
Microscopic magnetic beads are dropped into the solution that attach themselves to the virus RNA. The samples are then placed in a special machine that pulls the beads and RNA from the solution. This part of the process is automated to limit human error and to quickly process larger batches of tests.
The sample is then taken to an analyzer in a separate room. Lab workers add fluorescence that is attracted to the RNA, amplifying how well it can be seen by testing equipment. The analyzer will then indicate if the sample has coronavirus RNA or not.
The turnaround time for testing is 24-48 hours starting from when a swab gets to the lab. If the lab hits capacity, it pushes untested samples to the next day for processing.
The lab is seeing about a 3% positive rate from its testing.
How is someone notified of testing results?
A positive test result is passed on to a client support team which manages what comes next. A team of trained nurses contact those with positive test results, to inform them of the results and provide guidance about what they should do next.
The lab also assembles a daily report for states' departments of health listing both positive and negative results.
Is there a concern with false positives or negatives?
The test won’t display false positives, Odenbrett said. The test won’t see the virus RNA if it is not there. But false negatives are possible, usually caused by bad samples.
Is Sanford going to expand its testing capability?
Sanford is hoping to set up testing in Fargo and additional testing capacity in Sioux Falls.
In Fargo, Sanford is setting up an analyzer that could process a test within an hour, for high-priority tests. But the analyzer can’t do many tests at a time, unlike the slower machines. That analyzer would be used to process high-priority tests from inpatients and health care workers from Sanford’s Fargo region.
In Sioux Falls, Sanford has on order another machine like the one it uses now, which will double the lab’s testing capability.
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