New test can tell if you've had coronavirus in the past

Here's what we know about the first widely available test of its kind that can tell whether someone has been infected with COVID-19 months after the fact.

Video Transcript

KATE LARSEN: We first met Rick St. John at Stanford in a special study of what's come to be known as long haul COVID. While his symptoms have persisted for months, he says in the beginning, they were mild enough that he almost went undiagnosed.

RICK ST. JOHN: I didn't have fevers and I didn't have a cough. And those were the criteria on which they used to authorize testing.

KATE LARSEN: After weeks, he was finally able to arrange a test that confirmed his diagnosis. But stories like Rick's may have left thousands of people across the country wondering if they might have been infected with COVID-19 in the past and never known it, either because they were never tested or had mild symptoms.

LANCE BALDO: And so trying to tease out what symptoms might or might not be due to having COVID in the past is incredibly important.

KATE LARSEN: Dr. Lance Baldo is the chief medical officer for Seattle-based Adaptive Biotechnologies. The company is now marketing the first widely available test of its kind to tell whether someone has been infected with COVID-19, even months after the fact. It employs a sophisticated process to detect the activity of T cells, which are a key part of the body's immune response.

LANCE BALDO: This T cell's fingerprint is lasting out to about nine or 10 months in about 90% of patients. And so we're able to see kind of beyond the typical window where you'd be able to pick up antibodies.

KATE LARSEN: Like a standard antibody test, a patient provides a blood sample, either at a nationwide testing company called LabCorp or with an at-home appointment. It's compared to markers developed by Adaptive in partnership with Microsoft. And the patient gets a result back in about seven to 10 days.

Dr. Sudeb Dalai is an infectious disease specialist and a senior medical advisor with Adaptive. He believes the test results could be critical for long-term COVID patients and their ability to find the right care.

SUDEB DALAI: It is important on an advocacy level for individuals not only to understand their own medical history and what they've been to, but to advocate for themselves.

RICK ST. JOHN: That then they have a confirmation that maybe it's associated with COVID. Then they can get more access to treatment.

KATE LARSEN: Kate Larsen, ABC7 News.

- And release. And release.