Imagine a world where a simple, natural supplement could make vaccines more effective and less daunting. Sounds too good to be true? Well, groundbreaking research from the University of California San Diego School of Medicine suggests it might not be. A fungal supplement, taken alongside the COVID-19 vaccine, has been shown to reduce side effects and boost long-term immunity, particularly in those never exposed to the virus. But here's where it gets even more intriguing: this discovery could revolutionize how we approach vaccination, potentially reducing hesitancy and the need for frequent boosters.
Published in BMC Immunology on March 3, 2026, the study focused on a four-day oral supplement called FoTv, derived from the mycelium (the root-like structure) of two medicinal fungi: Fomitopsis officinalis and Trametes versicolor. In a randomized, double-blind, placebo-controlled trial, 90 adults received either FoTv or a placebo alongside their COVID-19 vaccine. The results? Participants who took FoTv experienced fewer short-term side effects like fever, chills, and fatigue. Even more remarkable, their antibody levels continued to rise for up to six months—a stark contrast to the typical decline seen after vaccination.
But here’s where it gets controversial: While synthetic immune adjuncts in vaccines often come with increased side effects, this natural fungal supplement seems to do the opposite. Could this be the key to making vaccines more tolerable and effective? Gordon Saxe, MD, PhD, MPH, the study’s lead investigator, believes so. He notes, “Natural products are widely used but rarely tested rigorously. We wanted objective data, and FoTv delivered promising results.”
The study’s strongest findings were in “COVID-naïve” participants—those never infected or vaccinated before the trial. This group not only experienced fewer side effects but also saw their antibody levels climb steadily over six months. Saxe explains, “Typically, antibodies peak around one month post-vaccination and then decline. With FoTv, we saw a sustained increase, which is unprecedented.”
And this is the part most people miss: the implications go far beyond COVID-19. Fungal mycelium can be produced at scale using standardized, medical-grade methods, making it a potential game-changer for future infectious disease outbreaks, including threats like H5N1 avian influenza. Saxe adds, “With emerging threats like bird flu, we need affordable, scalable tools to strengthen vaccines without worsening side effects. FoTv could be that tool.”
But here’s a thought-provoking question: If fungi and humans share a common evolutionary ancestor, and human immune cells respond to fungal compounds, could we be overlooking a treasure trove of natural remedies? Fungi like FoTv may hold untapped medical potential, and this study is just the beginning. Saxe emphasizes that more research is needed to confirm these findings and understand how FoTv works.
The study was funded by grants from the UC San Diego Krupp Endowed Fund, the Jonathan and Kathleen Altman Foundation, Fungi Perfecti, LLC, and others. The FoTv supplement was provided by Fungi Perfecti, LLC, and the authors declared no competing interests. Saxe, who serves on the Krupp Endowed Fund board, was recused from grant decision-making.
So, what do you think? Could natural supplements like FoTv reshape the future of vaccination? Or is this just another promising but unproven idea? Let us know in the comments—we’d love to hear your thoughts!
