New Research Suggests High-Purity CBD May Help Block COVID-19 Virus From Replicating

The study, published on January 20, 2022, in Science Advances, found CBD showed a significant negative association with positive COVID tests in a national sample of medical records of patients taking the FDA-approved drug for treating epilepsy. The researchers now say that clinical trials should be done to determine whether CBD could eventually be used as a preventative or early treatment for COVID-19.

They caution, however, that the COVID-blocking effects of CBD come only from a high-purity, specially formulated dose taken in specific situations. The study’s findings do not suggest that consuming commercially available products with CBD additives that vary in potency and quality can prevent COVID-19.
An unexpected avenue

The idea to test CBD as a potential COVID-19 therapeutic was serendipitous. “CBD has anti-inflammatory effects, so we thought that maybe it would stop the second phase of COVID infection involving the immune system, the so-called ‘cytokine storm,’” said Marsha Rosner, Charles B. Huggins Professor in the Ben May Department of Cancer Research and a senior author of the study. “Surprisingly, it directly inhibited viral replication in lung cells.”

To see this effect, the researchers first treated human lung cells with a non-toxic dose of CBD for two hours before exposing the cells to the COVID virus and monitoring them for the virus and the viral spike protein. They found that, above a certain threshold concentration, CBD inhibited the virus’ ability to replicate. Further investigation found that CBD had the same effect in two other types of cells and for three variants of the COVID virus in addition to the original strain.

CBD did not affect the ability of the virus to enter the cell. Instead, CBD was effective at blocking replication early in the infection cycle and six hours after the virus had already infected the cell.

“No one in their right mind would have ever thought that it blocked viral replication, but that’s what it did.”

— Prof. Marsha Rosner

Like all viruses, the COVID virus affects the host cell by hijacking its gene expression machinery to produce more copies of itself and its viral proteins. This effect can be observed by tracking virus-induced changes in cellular RNAs. High concentrations of CBD almost completely eradicated the expression of viral RNAs. It was a completely unexpected result.

“We just wanted to know if CBD would affect the immune system,” Rosner said. “No one in their right mind would have ever thought that it blocked viral replication, but that’s what it did.”

The researchers showed that the mechanism by which CBD blocks the COVID virus replication involves CBD activation of one of the host cell stress responses and generation of interferons, an antiviral cell protein.

Real-world data: Patients taking CBD test positive for COVID-19 at lower rates

The researchers wanted scientific data to show that CBD prevents viral replication in live animals. The team showed pretreatment with CBD for one week prior to infection with the virus suppressed infection both in the lung and the nasal passages of mice. “These results provide major support for a clinical trial of CBD in humans,” said Rosner.

And the success of CBD wasn’t limited to the laboratory: An analysis of 1,212 patients from the National COVID Cohort Collaborative revealed that patients taking a medically prescribed oral solution of CBD for the treatment of epilepsy tested positive for COVID-19 at significantly lower rates than a sample of matched patients from similar demographic backgrounds who were not taking CBD.

The potential for CBD to treat patients recently exposed to or infected by DOI: 10.1126/sciadv.abi6110

Funding: BIG Vision grant from the University of Chicago, the National Institutes of Health, Harry B. and Leona M Helmsley Charitable Trust.