At the beginning of the pandemic, it was believed that cannabis had no role in prevention or treatment of COVID and would, in fact, make you get sicker if you got the virus.

But now a spate of research is pointing toward the possibility that components of cannabis could prevent or treat COVID by interfering with the virus that causes the disease, and that cannabis users who get COVID may have better outcomes than nonusers.

A series of studies supported by the National Institutes of Health (NIH) tested the effects of CBD and other cannabis compounds on the COVID virus in human lung cells and in mice.

The studies also analyzed information from the National COVID Cohort Collaborative, which is compiling a huge amount of clinical data from health records of volunteers to help answer research questions addressing the pandemic. 

The researchers looked at the records of COVID patients who were already taking CBD for other conditions. The NIH posted a report about the studies on its website,, on April 4.

In both the lab studies and health records analysis, CBD appeared to have a protective effect against the virus, according to the report.

In the lab, when human lung cells were treated with CBD, the virus was unable to replicate and affect the host cells like it usually does.

Studies with mice found that the creatures dosed with CBD before being exposed to the virus were far less likely to get sick than others in a control group.

And in the studies of health records, human patients who took a CBD-based medication were less likely to get a COVID diagnosis than people who had not taken the medication.

The lab studies are uncovering how CBD works on a cellular level to block the COVID virus.

Researchers at the University of Illinois and the University of Chicago, supported by the National Institutes of Health, found that CBD blocked the replication of SARS-CoV-2, the virus that causes COVID, by inhibiting the activity of the virus’ genes and reversing many of the effects of the virus on the host cell’s genes.

The researchers treated human lung cells with CBD and then exposed the cells to the virus, which binds to human cells through a spike protein.

They observed that the virus was still able to enter the cells, but CBD stopped the virus from reproducing early in the infection cycle.

The researchers also studied the effect of CBD on viral replication in mice. They treated a group of mice with CBD for a week before infecting them with the COVID virus and found that CBD suppressed infection in the animals’ lungs and nasal passages,

“This study highlights CBD as a potential preventative agent for early-stage SARS-CoV-2 infection and merits future clinical trials,” the authors wrote in the Jan. 20, 2022, issue of Science Advances.

The researchers noted the CBD used in the experiments was high quality, pharmaceutical grade and administered in therapeutic doses, and that CBD — but not THC or other components of cannabis — had the therapeutic effect.

There’s precedent for the use of CBD preparations in treating health conditions.

One CBD medication has already been approved by the Food and Drug Administration (FDA) to treat seizure disorders. A group of those patients participated in the NIH COVID studies. Other CBD medications are in the development and testing stages, according to the National Institutes of Health.

Scientists also are investigating how cannabis consumption is associated with the severity of COVID cases.

Researchers at the David Geffen School of Medicine at UCLA found that hospitalized patients with COVID who had used cannabis had less severe cases of COVID than nonusers.

The study, published in the Journal of Cannabis Research on Aug. 5, analyzed the records of 1,831 patients admitted to two Southern California medical centers with a diagnosis of COVID, including the NIH COVID severity score, need for supplemental oxygen, admission to intensive care units, need for ventilation and length of hospital stay. 

Of the total patients, 69 reported active cannabis use. Those patients had better outcomes compared with nonusers, including better severity scores, shorter hospitalization (four days vs. six days), lower ICU admission rates (12 percent vs. 31 percent) and less need for mechanical ventilation (6 percent vs. 17 percent).

The researchers stated that their results should be interpreted with caution because of the small size of the sample and the limitations of a retrospective analysis. They cited the need for more studies to help scientists better understand the effects of cannabis use in COVID patients.

It’s important to note that these studies are not suggesting that anyone should use cannabis or CBD products to prevent or treat COVID infection. Health care experts still recommend getting vaccinated and boosted, wearing a mask and isolating if you’ve been exposed or get sick. 

Jeanne Davant is a graduate of the University of North Carolina. She worked for daily newspapers in D.C., North Carolina and Colorado, and has taught journalism and creative writing. She joined the Colorado Publishing House in 2017.