These assays commonly present false negative results if they are performed too soon after infection and no IgM was yet produced or present false positive results because of antibody cross reactivity with other Flaviviruses or other pathogens (Kerkhof et al., 2020; Musso and Desprès, 2020; da Rocha Queiroz Lima et al., 2021; Stiasny et al., 2021; Chan et al., 2022). Here, CD40LG is linked to infection.