For example, enhanced secretory mucosal IgA responses, detected in the circulation in severe COVID-19, were hypothesised to confer damaging effects via induction of inflammatory cytokines (169–171); although IgA levels in saliva from COVID-19 patients showed only a moderate correlation with COVID-19 severity (172) and other studies found no difference with disease severity (155). Here, CD79A is linked to COVID-19.