Complement activation was not increased in patients with post-acute sequelae after mild SARS-CoV-2 infection: A prospective cohort study

Dysregulation of the complement system has been proposed as a pathophysiological mechanism for Post-acute sequelae of SARS-CoV-2 (PASC). We analyzed the complement activation markers C3bc, C3bBbP and TCC in 48 PASC patients, grouped into whether they had a mild (n=38) or severe (n=10) acute SARS-CoV-2 infection, and 80 control subjects. Although the patients with a mild SARS-CoV-2 infection had a trend towards more severe PASC, we could not find any significant differences in complement activation markers between these patients and controls. In conclusion, we could not find convincing evidence of activation of the complement system in PASC patients.