General biomarker literature outside COVID shows serum PRDX4 can reflect systemic OS and worse outcomes in several conditions, suggesting plausibility; a small pediatric study proposes serum PRDX4 could help distinguish acute COVID-19 from MIS-C, but this is preliminary and not yet a validated prognostic tool for adult severity/mortality (Schulte, 2011; El-Ghany et al., 2024). This evidence concerns the gene PRDX4 and COVID-19.