Urine Tests May Be the Future of COVID Antibody Testing

If you’ve had COVID-19, you likely have antibodies to the SARS-CoV-2 virus in your blood. To know for sure, you would need to have a blood test to check for those antibodies.  

However, that might not be your only option in the future. A new study published in Science Advances found that using urine as a sample instead of a blood sample can be as effective at detecting anti–SARS-CoV-2 antibodies.

Urine vs. Blood COVID Antibody Tests

An important performance metric of an antibody test is how well it correctly finds antibodies when they are truly present (sensitivity) and how well it correctly identifies when antibodies are truly not present (specificity).

When the tests are accurate, it helps make sure that someone who really has COVID gets a positive test and someone who does not have COVID gets a negative test.

In the new study, the researchers developed a urine-based antibody test that had higher sensitivity (94%) than serum-based (blood) COVID antibody tests (88%). Both tests had 100% specificity.

Marc Sala, MD, a pulmonary and critical care specialist with Northwestern Medicine Comprehensive COVID-19 Center, said that the two kinds of antibody tests were found to be equally accurate in the study, which used urine and blood samples collected at the same time from hospitalized and non-hospitalized patients.

Potential Benefits of Urine-Based Antibody Tests

Serum-based (blood) antibody tests are accurate and have a low rate of complications, but a urine-based test would still be useful for providers and patients.

Beth Oller, MD, family physician at Solomon Valley Family Medicine, told Verywell that, unlike blood samples, urine can be self-collected by patients and does not require a trained phlebotomist.

Urine samples are also convenient for clinical practice because they’re easier to handle and store than blood samples. Self-collection of a sample would also make a urine-based test much cheaper than a blood test.

However, Oller said that the main benefit of urine-based COVID antibody testing is that people will probably be more comfortable giving a urine sample than having their blood drawn since it’s less invasive.

Sala added that a non-invasive test urine test would be helpful for children since it can be hard to get a blood sample from kids.

You Can’t Get a Urine COVID Antibody Test—Yet

Although the study showed promising results, urine-based COVID antibody tests are not market-ready just yet.

According to Sala, the study’s findings (which came from a small sample) would need to be validated in a larger group first because there are some aspects that still aren’t clear to researchers.

For example, Sala said that providers would need to know if the antibodies in a patient’s urine rise and fall over time with the same pattern (as the antibodies found in the blood do) or if a person’s kidney function could affect the results of the test.

Oller added that if the goal is to make the test commercially available for at-home use, it would need to get authorization from the Food and Drug Administration (FDA). An emergency use authorization (EUA) would likely be issued first.

A urine test could also be made available for point-of-care testing at a laboratory, walk-in clinic, or a provider’s office.

“Overall, this is very exciting because it could very well mean that there could be ways to test for antibodies for other viruses and infections the same way,” said Oller. “It could simplify some testing possibly by doing urine tests versus blood tests, which could also make testing more affordable.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.