London researchers discover novel method to diagnose long COVID


Study found unique blood biomarkers in patients with post-COVID-19 condition

LONDON, ON – Published this week in Molecular Medicine, researchers at Lawson Health Research Institute have found that patients with post-COVID-19 condition (long COVID) have unique biomarkers in their blood. The team is now working on developing a first of its kind blood test that could be used to diagnose long COVID. The discovery could also lead to new therapeutics for this condition.

Long COVID occurs when someone experiences symptoms like fatigue, cognitive issues, shortness of breath and gastrointestinal issues after an initial COVID-19 diagnosis. It can sometimes take up to 12 months for the condition to occur.

“It’s estimated that 30 to 40 per cent of patients with COVID-19 will develop long COVID,” says Dr. Douglas Fraser, Lawson Scientist and Critical Care Physician at London Health Sciences Centre (LHSC). “Physicians currently rely on symptoms alone to diagnose the condition, but our research offers a unique profile of blood biomarkers that could be used in a clinical test.”

The researchers studied 140 blood samples from participants at LHSC and St. Joseph’s Health Care London, including St. Joseph’s Post-Acute COVID-19 Program. Participants were those with presumed long COVID, hospital inpatients with acute COVID-19 infection and healthy control subjects.

“We chose to study blood vessels that link all the body systems together to look for changes after an acute infection,” explains Dr. Fraser, who is also a Professor at Western University’s Schulich School of Medicine & Dentistry.

The team found that blood vessels of those with presumed long COVID were changing rapidly after a confirmed COVID-19 infection. They also found that patients with long COVID had 14 elevated blood biomarkers associate with blood vessels. With the help of machine learning, they discovered that two biomarkers called ANG-1 and P-SEL could be used to classify long COVID with 96 per cent accuracy. 

“Long COVID is a relatively new condition and we have much to learn about it,” says Dr. Michael Nicholson, Associate Scientist at Lawson, Respirologist at St. Joseph’s and Associate Professor at Schulich Medicine & Dentistry. “This research advances our understanding of long COVID with the potential to improve diagnosis and patient care.”

The advantage of biomarkers is that they not only help diagnose a disease but also provide insight into potential treatments. The team is now focused on using their findings to create a clinical diagnostic test with a goal of also exploring therapeutics.

“With a point-of-care diagnostic test, we could confidently diagnose long COVID and eventually develop targeted therapeutics against these blood vessel changes that we have discovered,” says Dr. Fraser. “The ultimate goal is to improve patient outcomes following a long COVID diagnosis.”

This research was supported by funding from London Health Sciences Foundation, London Community Foundation and the AMOSO Innovation Fund. It builds on a growing body of COVID-19 research from scientists at Lawson Health Research Institute. 

About Lawson Health Research Institute

Lawson Health Research Institute is one of Canada’s top hospital-based research institutes, tackling the most pressing challenges in health care. As the research institute of London Health Sciences Centre and St. Joseph’s Health Care London, our innovation happens where care is delivered. Lawson research teams are at the leading-edge of science with the goal of improving health and the delivery of care for patients. Working in partnership with Western University, our researchers are encouraged to pursue their curiosity, collaborate often and share their discoveries widely. Research conducted through Lawson makes a difference in the lives of patients, families and communities around the world. To learn more, visit

Media Contacts
Celine Zadorsky

Communications Consultant & External Relations
Lawson Health Research Institute
T: 519-685-8500 ext. 75664
C. 519-619-3872