From the outset of the pandemic, the prospect that weed might be used to fight COVID-19 was tantalizing. After all, many people across the planet were getting high to pass the time during lockdown, and there is a long history of governments shunning the idea that cannabis might have health benefits, research be damned.
Still, the FDA and other health authorities were quick to say as far back as April 2020 there was no science to back up claims that weed was going to be useful in warding off the deadly disease.
That may have been premature. New, peer-reviewed research published Thursday in Science Advances suggests the popular non-psychoactive compound in cannabis known as cannabidiol, or CBD, can help prevent the novel coronavirus from replicating in human cells, reducing the chances of a full-blown infection. Another arm of the study also found that real-world patients who were prescribed CBD experienced lower rates of COVID-19.
“We just wanted to know if CBD would affect the immune system,” Marsha Rosner, a cancer biologist and expert in cell stress at the University of Chicago and a senior author of the new study, said in a statement. “No one in their right mind would have ever thought that it blocked viral replication, but that’s what it did.”
Rosner and her colleagues don’t yet recommend consuming CBD products—nor do they believe CBD could be a substitute for vaccination (still by far the best way to protect yourself). But the authors do advocate launching clinical trials soon to more rigorously probe whether it could be used as an additional therapeutic to prevent or slow down breakthrough COVID, an especially urgent task in light of the Omicron variant’s seemingly relentless spread.
In the first part of the study, authors exposed human lung cells in the lab to CBD for a couple hours before exposing the same cells to SARS-CoV-2 (the virus that causes COVID-19). They found that while the virus was still able to enter the cells, CBD inhibited the virus from hijacking the human cell machinery to replicate its own viral genome—an essential step for an infection to spread. The authors believe CBD boosts the production of an antiviral cell protein and other host cell responses that basically put a lockdown on gene replication.
The effects were the same in tests of two other types of human cells, for three different SARS-CoV-2 variants altogether (unfortunately big variants like Omicron and Delta were not tested). The team also treated live mice with CBD for a week before exposing them to COVID-19, and witnessed the same suppression of infection.
The second part of the study was a survey of 1,212 human patients who’ve been prescribed an oral CBD solution for the treatment of epilepsy, and showed only 6.2 percent had returned positive tests for COVID-19, compared to 8.9 percent of similar patients not taking CBD. Among patients who reported taking CBD the day they went in for a COVID-19 test, only 4.9 tested positive, compared to 9 percent in the control group.
But don’t go making plans to stock up on weed gummies or other cannabis products to protect yourself from COVID. Rosner specifically emphasized that “the commercially available CBD powder we looked at, which was off the shelf and something you could order online, was sometimes surprisingly of high purity but also of inconsistent quality.”
Still, it’s becoming less and less tenable to oppose deeper study of the relationship between cannabis and COVID. The new findings come just a week after Canadian researchers published their own study finding that other cannabis compounds exhibited anti-COVID effects as well.
“We are very eager to see some clinical trials on this subject get off the ground,” Rosner said. “Especially as we are seeing that the pandemic is still nowhere near the end, determining whether this generally safe, well-tolerated, and non-psychoactive cannabinoid might have antiviral effects against COVID-19 is of critical importance.”