A previous study by Urra et al. reported an inverse correlation for IgG and IgM antibodies to alpha-Gal[Galα1–3Galβ1–3(4)GlcNAc] and COVID-19 disease severity; those with the most severe outcomes had the lowest levels of α-Gal antibodies.45 In their study, COVID-19 patients as a group had lower antibody levels than healthy subjects. This evidence concerns the gene CD40LG and COVID-19.