Published on Mar. 4, 2026
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Researchers at the University of California San Diego School of Medicine have found that a natural fungal supplement taken at the time of COVID-19 vaccination reduced short-term vaccine side effects and helped antibodies last longer in people who had not previously been exposed to the virus.
Why it matters
Natural products are widely used but rarely tested in large, controlled clinical trials. This study provides objective data on a potential natural immune regulator that could decrease vaccine side effects while preserving or increasing antibody levels and vaccine protection.
The details
The study was a randomized, double-blind, placebo-controlled clinical trial that tested a four-day oral supplement made from the mycelium of two medicinal fungi. Participants took the supplement on the same day they received their COVID-19 vaccine. The strongest results were seen in ‘COVID-naïve’ participants, where those who took the supplement had significantly fewer side effects and continued to see increases in antibody levels over six months.
The study was published on March 3, 2026.Participants began taking the supplement on the same day they received their COVID-19 vaccine.
The players
Gordon Saxe
The study’s principal investigator and a professor in the Department of Family Medicine at UC San Diego School of Medicine.
Fungi Perfecti, LLC
The company that provided the mushroom mycelium of Agarikon and Turkey Tail (FoTv) used in the study.
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What they’re saying
“Natural products are widely used, but they are rarely tested at this level. We wanted objective data.”
— Gordon Saxe, Principal Investigator (Mirage News)
“Our goal was to see whether FoTv, a possible natural immune regulator, could decrease vaccine side effects while preserving or increasing antibody levels and helping vaccine protection last longer. The results suggest that it may have done both.”
— Gordon Saxe, Principal Investigator (Mirage News)
What’s next
Additional studies are needed to confirm the findings and better understand how the supplement works.
The takeaway
This study provides promising evidence that a natural fungal supplement could help reduce vaccine side effects and increase antibody durability, which could help address vaccine hesitancy and potentially reduce the need for frequent booster shots.
