Discussion
LEAKAGE
The microbiota is fundamental for health and the evolution of the immune system with the microbiota is interconnected (That the oral microbiome community might regulate local vaccine-induced mucosal immunity is intriguing and to our knowledge, similar results have not been reported before for other COVID-vaccines. The findings are of interest for vaccine strategies that aim at improving the mucosal immune memory. Although the precise mechanistic role of oral microbiota in vaccine response is unknown, several potential mechanisms could explain the link between deferentially enriched oral taxa and the persistence of salivary spike-IgG in the vaccinees. While most salivary IgG antibodies are derived from the bloodstream by passive leakage of the periodontal epithelium, there can also be some local production by salivary gland plasma cells (Our study design had considered age, sex, and BMI, which are all associated with vaccine efficacy against SARS-CoV-2 (In conclusion, our study is the first to demonstrate that oral microbiome may have a role in maintaining the long-term antibody persistence in saliva and in blood after COVID-19 mRNA vaccination. Including oral health- or microbiome-targeted interventions to improve the long-term mucosal memory after vaccination should be further explored.