New-Onset Complement-Mediated Thrombotic Microangiopathy during the COVID-19 Pandemic

Introduction:The coronavirus disease-19 (COVID-19) iscaused by the severe acute respiratory syndrome co-ronavirus 2 (SARS-CoV-2). Thevirusisallegedtoenableaproinflammatory state that leads to the activation of thecoagulation and the complement cascade. In this study,we aimed to establish the impact of the COVID-19pandemic on patients with new onset of cTMA/aHUS inthe Vienna TMA cohort and whether COVID-19 or SARS-CoV-2 vaccinations would pose a greater risk of initialmanifestation of cTMA/aHUS.Methods:We used theVienna TMA cohort database to examine the prevalenceof COVID-19-related and of SARS-CoV-2 vaccination-related aHUS/cTMA during thefirst 3 years of the CO-VID-19 pandemic in a large single-centre cohort.Results:Between March 2020 and May 2023, a total of 7patients experienced theirfirst aHUS/cTMA episode. Nopatient experienced a TMA relapse or more than oneepisode during the follow-up period. Three TMA epi-sodes were attributable to either COVID-19 (n= 1; 33%)or SARS-CoV-2 vaccination (n= 2; 66%), respectively. All3 patients had systemic signs of TMA, and TMA wasconfirmed by kidney biopsy in all cases. Among the 7patients, we recordedfive infections that triggered oneTMA episode (20%) and 19 vaccinations triggered twoTMA episodes (10%;p= 0.52, odds ratio 0.47; 95% CI:0.04-8.39).Conclusion:We speculate that both SARS-CoV-2 vaccinations and COVID-19 episodes can repre-sent a triggering factor for aHUS/cTMA episodes in(genetically) vulnerable individuals. However, COVID-19might have a stronger association and might be astronger trigger than the SARS-CoV-2 vaccines. The in-cidence of new aHUS cases did not differ from the pre-pandemic era in a large tertiary care centre cohort.(c) 2024 The Author(s).Published by S. Karger AG, Basel