Gut bacteria, flagellin and fever after mRNA vaccination in 171 adults
Thumbnail from YouTube. Playing loads the YouTube player.
History & recommendationsOff
Keep recently viewed content on this browser. Your history stays on this device and is never sent to Harbor. Videos you play can also help order related video recommendations.
Open saved items & history →At a glance
Automatic summary · not editorially reviewedIn the described study, 171 healthy adults were examined before and after an mRNA SARS-CoV-2 vaccine; those with more intestinal inflammation or higher flagellin expression before vaccination were more likely to develop fever, while antibody responses appeared unaffected. [1]
The described study examined gut microbiomes, body temperatures and blood-based immune markers of 171 healthy adults before and after an mRNA SARS-CoV-2 vaccine. [1]
Participants with greater intestinal inflammation or higher flagellin expression before vaccination were more likely to develop fever after vaccination. [1]
Flagellin, inflammation and dietary factors did not appear to affect antibody responses, and further research is needed on dietary interventions. [1]
Microbiome, temperature and immune markers in 171 adults
The description reports a study led by Kelsey Huus that examined the gut microbiomes, body temperatures and blood-based immune markers of 171 healthy adults before and after they received an mRNA vaccine against SARS-CoV-2. The stated aim was to investigate biological factors behind differences in vaccine-related fever, which the description says remain poorly understood. Fever and flu-like symptoms are described as common reactions, particularly after mRNA and lipid nanoparticle-based vaccines. [1]
Flagellin and prior inflammation linked to later fever
According to the description, certain gut bacteria, particularly members of the Lachnospiraceae family, produce flagellin, a protein that can activate inflammatory immune pathways. Participants with greater intestinal inflammation or higher flagellin expression before vaccination were more likely to develop a fever following vaccination. The description also reports associations between dietary patterns and microbiome activity, and says dietary manipulation altered microbiome composition and associated vaccine responses. These are described associations, not proof that diet causes less fever. [1]
Antibody responses reportedly unaffected; confirmation still needed
The description states that flagellin, inflammation and dietary factors did not appear to affect antibody responses, so increased inflammatory reactions did not necessarily mean changed vaccine-induced immunity. It also says further research is needed to establish whether dietary interventions can reliably reduce vaccine-related fever while preserving protection against infections. The description frames targeting gut bacteria and possibly modifying diet as a future possibility, not a current recommendation. [1]
Context & limits
This is a video description only; the video and transcript were not reviewed. The description summarizes a study and does not give full methods, effect sizes or the design details needed to judge causality. Reported links are associations, and the dietary findings are described only briefly.
Based on the creator’s description; the full video and transcript were not analyzed.
Quoted passages in the original language
examined the gut microbiomes, body temperatures and
more likely to develop a fever following
did not appear to affect antibody responses
About this video
Creator description · original textText language: English
Medical Dialogues · 3 min · Source published: 2026-10-12
Added to Harbor: 10/23/2026
Original on YouTube ↗Automatically categorized source. Creator statements are not an independent evidence review or personal medical guidance.