A new study from Brigham and Women’s Hospital suggests that persistent SARS-CoV-2 infection may be a contributing factor to Long COVID symptoms in some individuals. The research, published in Clinical Microbiology and Infection, found that patients experiencing a range of Long COVID symptoms were significantly more likely to have detectable coronavirus proteins in their blood, indicating ongoing viral activity.
Evidence of Persistent Infection
The study, led by Zoe Swank, analyzed over 1,500 blood samples from approximately 700 COVID-19 patients. The results showed that 43% of individuals with Long COVID symptoms affecting at least three major systems (cardiopulmonary, musculoskeletal, and neurologic) had viral proteins present in their blood between one to 14 months after initial infection, compared to only 21% of those without Long COVID symptoms.
Implications for Treatment
"If we can identify a subset of people who have persistent viral symptoms because of a reservoir of virus in the body, we may be able to treat them with antivirals to alleviate their symptoms," said Swank. This suggests a potential therapeutic avenue for a subset of Long COVID patients who may benefit from antiviral medications targeting the persistent viral infection.
Multiple Causes of Long COVID
However, the study also highlighted that more than half of the Long COVID patients did not have detectable viral proteins, suggesting that persistent infection is not the sole cause of Long COVID. "This finding suggests there is likely more than one cause of Long COVID," explained David Walt, principal investigator and professor of pathology at Brigham and Women’s Hospital. He proposed that immune system dysfunction resulting from the initial viral infection could be another contributing factor.
Understanding Long COVID Mechanisms
The researchers emphasize the need for further studies to fully understand the mechanisms underlying Long COVID. "There is still a lot that we don’t know about how this virus affects people," said Dr. David Goff, director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute. "These types of studies are critical to help investigators better understand the mechanisms underlying Long COVID -- which will help bring us closer to identifying the right targets for treatment."
The study utilized a highly sensitive test, Simoa, to detect even trace amounts of SARS-CoV-2 proteins in the blood samples. The researchers analyzed data from participants’ Long COVID symptoms, using electronic medical chart information or surveys that were gathered at the same time as the blood samples were taken. Commonly reported long COVID symptoms included fatigue, brain fog, muscle pain, joint pain, back pain, headache, sleep disturbance, loss of smell or taste, and gastrointestinal symptoms.
