A team of US researchers are conducting studies to understand whether botanical therapies like medicinal mushrooms and Chinese herbs provide therapeutic benefit in treating acute Covid-19 cases.
According to principal investigator Gordon Saxe, director of research at the Center for Integrative Health in University of California-San Diego, mushrooms were chosen because of their long history of use and recent evidence of immune-enhancing and antiviral effects.
MACH-19 (Mushrooms and Chinese Herbs for Covid-19) is a multi-centre study led by UC San Diego's School of Medicine and UC-Los Angeles, in collaboration with the La Jolla Institute for Immunology.
In a preclinical study published in 2019, mushroom agarikon was found to inhibit viruses, including influenza (H1N1), influenza A (H5N1) and herpes. Saxe said he believes medicinal mushrooms inhibit the viruses' replication, a theory he plans to test against SARS-CoV-2 in a Phase II trial.
"Mushrooms have the advantage that they co-evolved with us. So bacteria, viruses and other fungi prey on mushrooms just like they prey on humans. And mushrooms have developed exquisite defenses against those pests, and we believe they can confer those to us when we eat them," Saxe said.
MACH-19's third ongoing trial measures whether the same medicinal mushrooms, given in capsules at the time of initial Covid vaccination, can increase antibodies and other measures of immune response.
A fourth trial, yet to be launched, will look at whether medicinal mushrooms could provide a similar lift to Covid-19 booster shots as an adjuvant, a substance which enhances immune response.
"Vaccines lead to the production of antibodies that can destroy the virus in the blood," Saxe said.
"Mushrooms may not only increase the number of these antibodies, but also enhance T-cell immunity against virally infected cells. Further, because mushrooms bind to receptors on human immune cells, they can modulate our immunity -- boosting it in some ways and calming it down in others. And this property of mushrooms may also reduce vaccine-related side effects.
Natural therapeutics have been used for centuries to treat infectious diseases, according to Saxe, who noted that herbs helped Chinese doctors manage 300 recorded epidemics, while the Greek pharmacologist Pedanius Dioscorides prescribed agarikon to treat pulmonary infections 2,300 years ago.
The three trials, under MACH-19 of which two are Food and Drug Administration (FDA)-approved, are currently recruiting for between 66 and 80 patients who have tested positive for SARS-CoV-2 and who are quarantined at home with mild to moderate symptoms.AInitial safety data from the trials are expected by the end of this year, with efficacy data ready within a year.