Next-generation probiotic Bacteroides. dorei: Improving the efficacy of COVID-19 vaccinations

Bacteroides. dorei (B. dorei) is regarded as the "next-generation probiotics", and it has been demonstrated to fight influenza infection and alter the composition of gut microbiota. The role of the gut microbiota in the immune response to antiviral vaccination has been fully established in animal experiments and clinical studies. However, whether oral B. dorei can affect the immune response to COVID-19 vaccines remains unknown. This study reported that B. dorei enhanced SARS-CoV-2 vaccine efficacy as indicated by elevation in immunoglobulin G antibody and neutralizing antibody titers, mucosal immune response and Th1 immune response, and memory immune responses. Moreover, B. dorei alone could induce maturation of dendritic cells to promote Th1 response, which was crucial for antiviral immunity. These results suggest that B. dorei may potentially be used as an immunoadjuvant or immunopotentiator to enhance immune function, especially in individuals with impaired immune function.