Researchers say they have found the SARS-CoV-2 spike protein circulating in the blood of long COVID patients up to 12 months after they were diagnosed with COVID-19.
Researchers from Brigham and Women’s Hospital and Massachusetts General Hospital said the findings suggested the spike protein was a potential biomarker that could be helpful in diagnosing and treating long COVID patients.
They also said the findings bolster a theory that at least one cause of long COVID is the coronavirus lingering in a reservoir somewhere in the body even after a patient has recovered from a bout with the virus.
The study, which has not been peer reviewed, was posted last month on the medRxiv preprint site.
“Strikingly, we detect SARS-CoV-2 spike antigen in a majority of [long COVID] patients up to 12 months post-diagnosis, suggesting the presence of an active persistent SARSCoV-2 viral reservoir,” the study said.
The spike antigen was not detected in patients who recovered from COVID-19 but did not get long COVID.
Senior author David Walt of the Department of Pathology at Brigham and Women’s said several causes for long COVID have been hypothesized, including a persistent viral infection.
The study’s findings support that theory and suggest that “if someone could somehow get to that viral load and eliminate it, it might lead to resolution of symptoms,” he said.
Researchers, he said, are pondering whether to undertake a clinical trial to see if antiviral drugs will help long COVID sufferers.
The preprint study cited several other studies that have suggested the virus can linger in the body, including one by Walt and colleagues that found a reservoir of SARS-CoV-2 in the gastrointestinal tract of children who develop multisystem inflammatory syndrome.
Walt said researchers then thought, “Maybe that’s something we should look for in these long COVID patients, too.”
Dr. Amy Proal, a microbiologist at the PolyBio Research Foundation, a nonprofit that supports research into complex chronic inflammatory conditions, told the Guardian last month, “I don’t personally see a mechanism by which the spike protein would be able to persist over long periods of time without the virus [being present].”
Long COVID can include a wide range of symptoms, and the conditions can last weeks, months, or years, according to the US Centers for Disease Control and Prevention. Some symptoms include fatigue, brain fog, change in sense of taste or smell, gastrointestinal distress, and shortness of breath.
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