Natural Fungal Supplement Boosts Vaccine Protection

Researchers find a four-day oral supplement derived from medicinal fungi can reduce vaccine side effects and enhance antibody response.

Apr. 11, 2026 at 10:24pm

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An extreme close-up X-ray photograph revealing the delicate, translucent structure of fungal mycelium, conceptually representing the natural immune-boosting properties of medicinal mushrooms.A natural fungal supplement derived from medicinal mushrooms may hold the key to enhancing vaccine protection and reducing side effects.San Diego Today

Researchers at the University of California San Diego School of Medicine have discovered that a natural fungal supplement called FoTv, derived from the mycelium of two medicinal fungi, can reduce common vaccine side effects like fever and fatigue while also enhancing antibody levels in COVID-19 vaccine recipients, especially those without prior exposure to the virus.

Why it matters

This finding could help address vaccine hesitancy by providing a natural way to mitigate side effects, while also potentially reducing the need for frequent booster shots by prolonging the antibody response. The researchers suggest FoTv could be a valuable tool for future public health preparedness against emerging infectious threats.

The details

The study, a randomized, double-blind, placebo-controlled clinical trial, involved 90 adults receiving a COVID-19 vaccine. Participants were randomly assigned to take either FoTv or a placebo for four days starting on their vaccination day. In the group with no prior COVID-19 exposure, those who took FoTv experienced significantly fewer side effects and their antibody levels continued to increase over the entire six-month study period, rather than peaking and then declining as is typical.

  • The study was published on March 3, 2026, in BMC Immunology.
  • Participants started taking the four-day FoTv supplement on the same day they received their COVID-19 vaccine.

The players

University of California San Diego School of Medicine

The institution where the research was conducted and the researchers are affiliated.

Dr. Gordon Saxe

The lead investigator and a professor at UC San Diego School of Medicine who oversaw the study.

FoTv

A four-day oral supplement derived from the mycelium of two medicinal fungi, Fomitopsis officinalis and Trametes versicolor, that was the focus of 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.”

— Dr. Gordon Saxe, Lead Investigator and Professor, UC San Diego School of Medicine

“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.”

— Dr. Gordon Saxe, Lead Investigator and Professor, UC San Diego School of Medicine

“Antibody levels usually rise, peak about one month after vaccination, and then slowly decrease. In this group, we saw a significant decrease in vaccine side effects while, remarkably, antibody levels continued to increase up to the six-month mark.”

— Dr. Gordon Saxe, Lead Investigator and Professor, UC San Diego School of Medicine

What’s next

The researchers caution that further research is essential to confirm these findings and fully understand the mechanisms behind FoTv's beneficial effects.

The takeaway

This study suggests that a natural fungal supplement like FoTv could be a powerful tool for enhancing vaccine efficacy and reducing side effects, potentially addressing vaccine hesitancy and decreasing the need for frequent booster shots. The implications for future public health preparedness against emerging infectious threats are significant.