Three researchers across the globe are working to decipher the causes of long COVID-19 and determine the best ways to treat it, Science reported June 16.
Forty-nine percent of COVID-19 survivors reported persistent symptoms four months after infection, a meta-analysis of 31 global studies published April 16 in The Journal of Infectious Diseases found.
Although the syndrome has a still-evolving definition, many researchers studying its causes agree "solo operators" are unlikely. For example, a lingering virus could cause chronic inflammation in a patient. "I see this as a triangle," Dr. Danilo Buonsenso, a pediatric infectious disease physician in Italy, told Science.
Blood vessel damage and clots
Dr. Buonsenso suspects his patients have damage to the cells and tissues controlling blood flow, thus amplifying the tendency for clots. He scanned the lungs of 11 pediatric patients suffering from long COVID-19. Although six of the scans appeared normal, five showed irregular blood flow. He and his colleagues published the first evidence of the damage July 30 in The Lancet Child and Adolescent Health.
Persistent virus
Microbiologist Dr. Amy Proal is leading studies to explore the hypothesis that lingering virus particles — after acute infection — are driving symptoms in long COVID-19 patients. A number of studies have already shown "the virus is capable of persistence in a wide range of body sites," particularly nerves and other tissues," Dr. Proal, who works at the PolyBio Research Foundation in Washington, told Science. She is working with a team on research to see whether persistent virus can definitively be tied to symptoms.
Haywire immune system
Dr. Chansavath Phetsouphanh, an immunologist at the University of New South Wales in Australia, is delving into whether a revved-up immune system unable to stabilize after a COVID-19 infection is behind lingering symptoms. He and his colleagues led a study involving 31 long COVID-19 patients. By analyzing their blood, they found cells galvanized to battle the infection had not calmed down eight months after testing positive. "It was a surprise that these cells did not recover," he told Science.