Researchers have called for further studies to explore the role of cannabis in fighting Covid-19 as promising results from US laboratories left academics in shock.
In trials conducted at the University of Chicago, CBD was found to reduce the severity of infections in human cells and mice during the early stages of the virus.
It could even help prevent the spread of Covid in the first place, according to a research paper published in the journal Science Advances.
The findings, which took scientists by surprise, warranted the rapid development of further trials according to cancer research professor and senior author Marsha Rosner.
“We are very eager to see some clinical trials on this subject get off the ground, especially as… the pandemic is still nowhere near the end,” she said.
“Determining whether this generally safe, well-tolerated and non-psychoactive cannabinoid might have anti-viral effects against Covid-19 is of critical importance.”
Researchers at the university first treated human lung cells with a non-toxic dose of CBD for two hours before exposing the cells to Covid.
They found that above a certain threshold concentration, CBD limited the virus’s ability to replicate.
Although CBD did not affect the ability of Covid to enter the cell, it was effective at blocking replication early in the infection cycle and six hours after the virus had infected it.
“We thought maybe it would stop the second phase of Covid… no-one in their right mind would have ever thought it blocked viral replication, but that’s what it did.”
Research paper lead author marsha rosner
Further investigations found CBD had the same effect in two other types of cells and for three variants of Covid in addition to the original strain.
Rosner expressed huge surprise at the findings.
“CBD has anti-inflammatory effects so we thought that maybe it would stop the second phase of Covid infection involving the immune system, the co-called cytokine storm,” she said. “No-one in their right mind would have ever thought it blocked viral replication, but that’s what it did.”
In a second phase of the study, the research team turned their focus on live animals — with similar results.
According to academics, mice injected with 80 milligrams of CBD per kilo of weight one week before being infected with Covid saw the virus supressed in the lungs and nasal passages.
The results provide “major support” for a clinical trial of CBD in humans, Rosner said.
In further promising data, an analysis of 1,212 patients, whose medical records showed past use of a CBD product, tested positive for Covid at “significantly” lower rates than a sample of patients who were not taking CBD.
The research paper found 6.2% of those patients tested positive, rising to 8.9% for non-CBD patients.
“A clinical trial is necessary to determine whether CBD is really effective at preventing or supressing SARS-CoV-2 infection, but we think this may have potential as a prophylactic treatment,” Rosner said. “Maybe you’re in a hot spot or you think you might have been exposed or you’ve just tested positive. That’s where we think CBD might have an effect.”
Despite the encouraging results, researchers stressed people should not be fooled into believing CBD, or cannabis more widely, could be used as a first line of defence against Covid.
Rosner urged the public to get vaccinated and continue to follow government health advice.
She added: “Going to your corner bakery and buying some CBD muffins or gummy bears probably won’t do anything.
“What we don’t want… is people just running out and thinking, ‘I can take CBD, and then I don’t have to get vaccinated or I don’t have to be masked’. This is what we really don’t want to see.”
