Findings from the largest UK study of patients hospitalized with SARS-CoV-2 infection show that long COVID leads to ongoing inflammation which can be detected in the blood.

In an analysis of more than 650 people who had been hospitalized with severe COVID-19, patients with prolonged symptoms showed evidence of immune system activation.

The exact pattern of this activation varied depending on the sort of symptoms that they predominantly had—for example, mainly fatigue or cognitive impairment.

The research, led by Imperial College London, suggests that existing drugs which modulate the body’s immune system could be helpful in treating long COVID and should be investigated in future clinical trials.

The study, published in the journal Nature Immunology, is the latest research from two collaborative UK-wide consortia, PHOSP-COVID and ISARIC-4C.