Only a low proportion of individuals had anti-S- and anti-RBD IgM or IgA antibodies more than 6 months after infection confirming the faster decrease of the specific IgM and IgA antibody response observed in other studies (Anand et al., 2021; Dan et al., 2021; Roltgen et al., 2020; Xiang et al., 2021) although a few studies reported a high prevalence of specific IgA up to one year (Cohen et al., 2021; Wang et al., 2021c). This evidence concerns the gene CD40LG and infection.