Long COVID study finds no evidence of immune system overreaction
Researchers examining long COVID patients up to 33 months after infection found no significant activation of the complement immune system—challenging a leading theory about what causes persistent symptoms. The null finding matters: it narrows the list of potential biological culprits and could redirect funding and drug development toward other mechanisms.
Originaltitel: Complement activation in patients with post-acute sequelae after SARS-CoV-2 infection
Introduction Post-acute sequelae of SARS-CoV-2 (PASC) may develop after SARS-CoV-2 infection and cause a wide range of symptoms that can persist for years. Several pathophysiological mechanisms have been proposed, including dysregulation of the complement system. Methods In this study, we analysed markers of complement activation in a cohort of patients with PASC, up to 33 months after the initial infection. We measured the complement activation markers C3bc, C3bBbP and TCC in 38 PASC patients with an initial mild COVID-19 infection, 10 PASC patients with an initial severe COVID-19 infection and 80 control subjects who had recovered completely after a COVID-19 infection. Results Although the patients with an acute 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. Conclusion We could not find convincing evidence of activation of the complement system in PASC patients.