Did Studies Show That Marijuana Prevents COVID Transmission?
Two scientific papers published this month have added to the growing body of evidence indicating that cannabinoids may hold significant antiviral potencies and could potentially be used to create a prophylactic treatment for Covid-19.
The latest research into the impact of cannabinoid compounds on SARS-CoV-2 replication has generated a buzz on mainstream and social media, leading some users to claim that consumption of marijuana can help prevent or fight COVID infection.
“Now, if you’re skeptical about the science here, let me remind you, this study has been reviewed by the CDC’s stoner nephew the THC,” The Late Show host Stephen Colbert joked.
Stoner humor aside, the news also fueled mal- and misinformation. Some accounts pounced on the reporting to promote products containing CBD, the non-psychoactive cannabis compound featured in the research.
“We’re celebrating that CBD is officially scientifically proven to prevent Covid and the vaccine isn’t,” one tweet marketing CBD oil falsely claimed.
Since the start of the coronavirus pandemic, there has been a number of scientific studies exploring the potential links between cannabis and COVID-19, including a January 2021 study assessing antiviral potencies of cannabinoids against SARS-CoV-2 and an Israeli project to develop CBD-based treatments for the coronavirus in 2020.
More recently, a study, conducted in conjunction with Oregon State University and published in the Journal of Natural Products on January 10, indicated that cannabis compounds can be used as a “therapeutic agent” to block the COVID-19 virus from entering the body.
This week, a team of researchers from the University of Chicago claimed to have found evidence that cannabidiol (CBD) derived from a cannabis plant can inhibit infection by SARS-CoV-2 in human cells and in mice.
But while these and other studies into potential preventative or therapeutic treatments against the virus are encouraging, the headline-grabbing aspects of the research tend to obscure critical information and nuance in the findings, often leading to the proliferation of false or misleading interpretations.
As Newsweek previously reported, the peer-reviewed Journal of Natural Products found that “cannabigerolic acid (CBGA) and cannabidiolic acid (CBDA) prevented infection of human epithelial cells…and prevented entry of live SARS-CoV-2 into cells.”
But that conclusion came along with some major caveats, which poured cold water on the claims that recreational marijuana use is now “scientifically proven” to be effective at preventing COVID infection.
For one, the study involved testing against two early COVID variants, Alpha and Beta, but provided no data about the effects on the now dominant Omicron variant. It was also conducted in vitro, meaning that it assessed the impact of cannabinoid acids from hemp on human cells in a clinical setting, which may not necessarily be replicated in human trials.
The fact that the acid would need to be extracted from hemp leaves, as well as the high purity and quantity required for the effect to be tangible, ruled out the more widespread “methods of delivery,” such as smoking or consuming edibles with marijuana.
“Our infection inhibition assay results clearly indicate that CBDA and CBGA are both able to block cell entry by SARS-CoV-2. The concentrations needed to block infection by 50% of viruses is high but might be clinically achievable,” the research authors explained, reiterating that any potential treatment should be combined with proper doses of the COVID vaccine.
Meanwhile, the University of Chicago study, published on January 20 in Science Advances, claims in the abstract that “cannabidiol (CBD) inhibits infection of SARS-CoV-2 in cells and mice,” offering another cause for cautious optimism. But it, too, does not go so far as to justify the claims that marijuana products can prevent COVID infection, nor that they are “more effective than vaccines.”
This research, which included both cell-based findings, pre-clinical studies and analysis of patient data showing the link between CBD consumption and SARS-CoV-2 infection rate, concluded that “CBD and its metabolite 7-OH-CBD can block SARS-CoV-2 infection at early and even later stages of infection.”
It also supported previous findings that the substance “suppresses cytokine activation in response to viral infection, reducing the likelihood of immune cell recruitment and subsequent cytokine storms within the lungs and other affected tissues.”
But the authors also highlighted a number of issues, both with regards to using existing commercial products for prevention and treatment of COVID, and developing new ones.
While CBD-containing products are available on the market, they note that these products vary vastly in quality, CBD content, and their pharmacokinetic properties after oral administration, which is mostly unknown. Additionally, the quantity and purity of CBD in the existing products were deemed insufficient, while additional compounds found in cannabis such as THC could be detrimental to the antiviral effects.
“This essentially eliminates the feasibility of marijuana serving as an effective source of antiviral CBD, in addition to issues related to its legal status,” the study concludes, noting that “other means of CBD administration such as vaping and smoking raise additional concerns about potential lung damage.”
While cautioning against the use of CBD in “presently available formulations including edibles, inhalants or topicals as a preventative or treatment therapy,” the researchers call for further studies and clinical trials to be conducted in order to establish the optimal means of the compound’s delivery to patients.
A number scientific studies into the effects of CBD or compounds derived from cannabis on SARS-CoV-2 virus transmission have indeed shown promising results. These studies, however, did not broadly assess possible medicinal qualities or antiviral properties of the marijuana plant—which contains many other compounds in addition to CBD—and its recreational use. Researchers also explicitly warned against the use of existing means of CBD delivery, such as edibles or inhalation, for treatment or prevention purposes, and highlighted the importance of vaccinations against COVID.
FACT CHECK BY NEWSWEEK