Some thoughts about this conference abstract, presented at the ACG 2022 – see: https://www.eventscribe.net/2022/ACG-Posters/PosterTitles.asp?pfp=BrowsebyTitle
The title includes the wording “persistent damage” – but the abstract fails to show that a decrease in Bifidobacterium is bad for the microbiome or for its human host in adulthood. Although Bifidobacteria have a clear role early in life, as they can consume human milk oligosaccharides, and are suspected to be important in health even in adulthood, the gut microbiome of adult Hadza hunter-gatherers in Tanzania has been shown to contain undetectable levels of Bifidobacteria – see: https://www.nature.com/articles/ncomms4654 . Therefore, the absence of Bifidobacteria in adulthood is not necessarily a Very Bad Thing. The authors of this ACG abstract might show a decrease of Bifidobacterium over time, but they do not show that this is damaging. The title, therefore, is misleading.
How many subjects did the author include in their initial selection? Did they start with more than four and only include four subjects that showed a decrease in Bifidobacteria, or did they only select four to begin with?
It seems such a small number of subjects to make such a big statement. According to ClinicalTrials.gov, the first author has at least 7 clinical trials related to microbiome testing in COVID-19, several of which started in 2020 (e.g. NCT04334512), so the number of initially sequenced subjects might have been much higher than 4? Perhaps the authors can shed some light on this.
With only four subjects, how significant were these results? Bacterial taxa might show some natural fluctuation over time, so could these chances just be a coincidence? Without any control group (unvaccinated subjects) it is hard to know.
Alternatively, the subjects in this study might have changed their behavior after the vaccination. In those months, COVID lockdowns could have ended, the subjects might have started socializing again, stopped eating self-baked sourdough bread, stopped drinking self-fermented kefirs or kombuchas or any other change in lifestyle. There is no wording about that.
In one of the four subjects, the amount of Bifidobacteria actually largely increased after vaccination.
Can the authors perhaps clarify the time interval between the samples taken pre-vaccine and the vaccination itself? Were there samples taken days before vaccination? weeks? months?
The authors write “Although a small sample, these findings may suggest a potential mechanism for post-vaccination complications; however, no subjects in the study demonstrated significant complications.” This sounds very speculative. None of the four subjects had vaccination side effects, so how could these findings suggest a possible mechanism? And what would the mechanism be? There are no data presented on any mechanism, just on a drop of one bacterial genus after COVID-19 vaccination. This sentence is very speculative and appears to suggest that authors are trying to spin these findings toward an anti-vaccination position.
The authors write: “Gut dysbiosis post mRNA SARS-CoV-2 vaccines could potentially be a future indication for restoration of Bifidobacteria either orally or directly via fecal transplant.” I am not sure what the rules are for disclosing conflicts of interest in a conference poster, but the first author has several relevant patents filed before the presentation of this poster in October 2022, e.g. US20210290697A1, US20220120746A1, and CA3149221A1, according to patents.google.com. The last author has some other relevant patents filed as well, including JP2022009354A or US11541080B2. Were these conflicts of interest disclosed on the poster?