Abstract
Background: Use of fungal mycelium as a vaccination adjunct may constitute a novel antiviral strategy to address newly emerging viruses. We evaluated safety and feasibility of a fungal mycelium-based natural product (Fomitopsis officinalis and Trametes versicolor, FoTv) as an adjunct to human COVID-19 vaccination, as well as its impact on vaccine side-effects and anti-SARS-CoV-2 antibodies (Abs).
Methods: Randomized, double-blind, placebo-controlled clinical trial involving adjunctive treatment with FoTv or visually-identical Placebo (dosage: eight 500-mg capsules TID orally for four days) in combination with COVID-19 vaccination. Main outcomes included: Safety (adverse events, renal and hepatic function [Days 1–14]); Feasibility (completion rate and treatment adherence); Side-effects (number and severity, self-reported on days 1 [vaccination] to 5); and anti-SARS-CoV-2 Ab levels (receptor-binding domain and Spike, collected from blood drawn on days 1, 3, 14, and 28/42, and at 6 months).
Results: Ninety participants receiving COVID-19 vaccination were randomized to either FoTv (N = 52) or Placebo (N = 38) groups. There were no adverse events and the groups had overlapping 95% confidence
intervals for the percentage of participants transitioning from normal to abnormal renal/hepatic function when comparing Days 1 and 14. All participants (100%) completed the study and treatment adherence was greater than 95%. Participants with detectable anti-SARS-CoV-2 Abs (from prior COVID antigen exposure) were classified as “COVID-Exposed” and those with undetectable anti-SARS-CoV-2 Abs as “COVID-Naive.” FoTv, versus Placebo, significantly reduced side-effects in COVID-Naive individuals, specifically on days 3 and 5, but not in COVID-Exposed individuals. In the COVID-Naive FoTv group, Ab responses were preserved across 6 months (and possibly increased), an effect not observed among other groups.
Conclusions: After COVID-19 vaccination, adjunctive FoTv was safe, feasible, and reduced vaccine side-effects without compromising (and possibly increasing) Ab levels up to 6 months in participants without previous SARS-CoV-2 exposure. Use of fungal mycelia was successfully tested as a unique approach to prevent a novel pandemic virus (SARS-CoV-2), with potential application to H5N1/Bird Flu and other emerging viruses.
Trial registration: Trial registered on ClinicalTrials.gov NCT04951336 on June 30, 2021.
Saxe, G., Smith, C. N., Golshan, S., Shekhtman, T., Bair, Z. J., Beathard, C., Davis, R. A., MacElhern, L., Shubov, A., Slater, D., Kao, L. K., Senowitz, P., & Wilson, S. (2026). Polypore mushroom mycelia as an adjunct to COVID-19 vaccination: A randomized clinical trial. BMC Immunology, 27(1), 24. https://doi.org/10.1186/s12865-026-00809-9