We first assessed IgM immunogenicity at 1-week post-infection in the symptomatic cohort and classified 15 antigens as IgM-positive (more than 2 SD above baseline), including both IgG-immunogenic (n = 8) and non-IgG-immunogenic (n = 7) antigens (Additional File 1: Fig. S5). This evidence concerns the gene CD40LG and infection.