The profound increase observed not only in SARS-CoV-2-directed IgG- but also in IgA-antibodies after booster vaccination deserves consideration, as IgA-type antibodies are thought to play an important role in mucosal immunity and COVID-19 naïve individuals developed considerably weaker specific IgA-antibody responses after vaccination (Fig. 2c, d). The gene discussed is CD79A; the disease is COVID-19.