CD40LG and COVID-19: Five (5) peptide epitopes significantly associated with COVID-19 mortality in the discovery cohort were also observed in the validation cohort (p value ≤ 0.05; z-score >1.96 in ≥3 serum samples), including IgM antibodies to nsp3_1918-1922 and IgG antibodies to nsp2_446-450, ORF3a_176-180, ORF3a_216-220, and N_226-230 (Fig. 7c).