Gut microbiome composition linked to post-vaccination fever

Research published in the journal Science indicates that the composition of an individual's gut microbiome may influence the likelihood of experiencing fever and inflammatory responses following vaccination.

A study involving healthy adults receiving SARS-CoV-2 mRNA vaccines found that those who experienced a temperature increase of at least 0.8°C possessed distinct biological features prior to vaccination. These included low-grade intestinal inflammation and gut microbiomes rich in flagellated bacteria from the Lachnospiraceae family. These bacteria express flagellin proteins that activate Toll-like receptor 5 in immune cells, triggering inflammation.

The international study, involving researchers from the Max Planck Institute for Biology, Institut Pasteur, Inserm, and universities in the United States and Canada, also noted that vegetarians and vegans were less likely to experience post-vaccination fever. Importantly, these microbiome characteristics and dietary patterns did not appear to compromise the actual immune protection provided by the vaccines. Researchers suggest that dietary interventions to remodel the gut microbiome could potentially be used to reduce adverse reactions and improve vaccine uptake.