Remarkably, this gut microbe pair provided complete protection against SARS-CoV-2 infection (Figures 5,6), with a comparable or even superior level of protection compared to the current mRNA COVID-19 vaccines from Pfizer and Moderna.42,43 Since the gut microbe pair confers protection through host-directed vaccination by activating CD8+ cells (Figure 7), rather than relying on antigen-induced active immunity, it suggests that this gut microbe pair may offer broad protection against various pathogens. The gene discussed is CD8A; the disease is COVID-19.