Ontario researchers say they've found what causes long-COVID symptoms

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Researchers at Western University in London, Ont., say they have identified for the first time the cause of long COVID symptoms.

According to a press release issued Tuesday by Western, the LIVECOVIDFREE study, which is based at five centres throughout Ontario and spearheaded by Western professor Grace Parraga, is the largest MRI study of patients afflicted with long COVID.

The use of MRI technology — combined with inhaled xenon gas — allowed researchers to see that long-COVID symptoms are related to the microscopic abnormalities that affect how oxygen is exchanged from the lungs to the red blood cells.

The results of the study were published in the journal Radiology and reveal a potential cause for long-COVID symptoms.

“By understanding the cause, team members responsible for patient care have been able to target treatment for these patients,” the press release reads.

Long COVID is characterized by the feeling of brain fog, breathlessness, fatigue and limited capacity to do normal day-to-day things. The symptoms can last weeks or months following initial infection.

“I think it is always a conundrum when someone has symptoms, but you can't identify the problem. Because if you can't identify the problem, you can't identify solutions,” said Parraga, Tier 1 Canada research chair in lung imaging to transform outcomes at Western’s Schulich School of Medicine & Dentistry.

By having study participants inhale polarized xenon gas while inside an MRI, researchers could see in real time the function of the 300-500 million tiny alveolar sacs, which are about 1/5 of a mm in diameter and are responsible for delivering oxygen to the blood.

“With our MRI technique, we can watch in real-time the air moving through the alveolar membrane and through to the blood cells; and we can actually see the function of the tiny alveolar sacs in the lungs,” said Parraga. “What we saw on the MRI was that the transition of the oxygen into the red blood cells was depressed in these symptomatic patients who had had COVID-19, compared to healthy volunteers.”

Study participants with suspected long COVID were recruited from two London, Ont., hospitals -- London Health Sciences Centre's (LHSC) urgent COVID-19 care clinic and St. Joseph’s Health Care's post-acute COVID-19 program.

According to the release, some study participants were still symptomatic after 35 weeks. A one-year follow-up is now underway to better understand the results.

The study was done in collaboration with LHSC, St. Joseph’s, Lakehead University, McMaster University, Toronto Metropolitan University and Sick Kids Hospital in Toronto.