Gut microbiome and dietary fibre intake strongly associate with IgG function and maturation following SARS-CoV-2 mRNA vaccination

The first study to investigate potential associations between gut microbiota composition and SARSCoV2 vaccine immunogenicity was recently published in Gut. This study demonstrated a statistically significant reduction in alpha diversity and a shift in gut microbiota composition following BNT162b2 vaccination, characterised by reductions in Actinobacteriota, Blautia, Dorea, Adlercreutzia, Asacchaobacter, Coprococcus, Streptococcus, Collinsella and Ruminococcus spp and an increase in Bacteroides cacaae and Alistipes shahii. Our prospective observational study (n=52; figure 1A, online supplemental table S1) similarly showed a shift in gut microbiota after the first BNT162b2 vaccine dose (p=0.016; online supplemental figure S1A), including a reduction in Actinobacteria, Blautia spp (p<0.01; figure 1B), and alpha diversity (p=0.078; online supplemental figure S1B). Our data support the findings by Ng et al, reinforcing the link between SARSCoV2 mRNA vaccine immunogenicity and the gut microbiota. Ng et al also identified strong associations between baseline gut microbiota composition and serological IgG responses to BNT162b2 vaccination. After stratifying participants as low or high vaccine responders, they showed higher abundances of Eubacterium rectale, Roseburia faces, Bacteroides thetaiotaomicron and Bacteroides spp OM0512 were associated with stronger BNT162b2 vaccine responses. Correspondingly, in our cohort, several baseline bacterial taxa significantly differed between participants with low versus high BNT162b2 vaccine responses. Specifically, we observed higher baseline counts of Prevotella, Haemophilus, Veillonella and Ruminococcus gnavus Letter