In our study, we noted an increase in specific anti-S RBD-IgA levels in the pleural cavity, and this corroborated with previous findings associating with mild COVID-19 infections where anti-S RBD-IgA levels were elevated at different mucosal tissues in recovered COVID-19 patients (Sterlin et al., 2021; Yu et al., 2020). The gene discussed is CD79A; the disease is COVID-19.