Elevations in sC5b9 correlate with renal dysfunction. (A) Elevated sC5b9 levels in patients with minimal COVID-19 (n = 21), severe COVID-19 (n = 11), and MIS-C (n = 18) are significantly different relative to those of healthy control subjects (n = 26). (B) sC5b9 levels are significantly higher in those with AKI (n = 9) than without AKI (n = 38). Increases in sC5b9 levels in patients with all 3 manifestations of disease (N = 48) correlate in a statistically significant manner with elevations in creatinine (C) and in elevations of blood urea nitrogen (BUN; D) and GFR (E). Dotted line indicates upper limit of normal cutoff for sC5b9 of 247 ng/mL.