Scientists have identified an immune-system signature for long COVID, shedding light on the biological underpinnings of this mysterious condition1.
As many as 30% of people infected with SARS-CoV-2 go on to be affected by long COVID, which causes debilitating symptoms — including fatigue and shortness of breath — months after an initial infection with the virus. How the pathogen wreaks sustained havoc in the body remains unclear.
Chansavath Phetsouphanh at the University of New South Wales in Sydney, Australia, and his colleagues analysed blood samples from people with long COVID and found that a SARS-CoV-2 infection elicits an immune response distinct from that of other types of coronavirus, such as those that cause the common cold.
This response persists in people experiencing long COVID. The team’s analysis pointed to a collection of immune-system molecules that remained abnormally high in individuals with long COVID eight months after infection. These molecules, such as type 1 and type 3 interferons, are usually made at the time of a viral infection. They activate immune cells called T cells and trigger inflammation.
The findings could help researchers to develop treatments for the disorder.
