There have been numerous headlines in the media claiming that cannabis, specifically the cannabinoid tetrahydrocannabinol (THC), can help fight some of the symptoms associated with COVID-19. This is not just wishful thinking. The claim is based on a study that was conducted at the University of South Carolina where researchers tested to see if THC could reduce the severity of Acute Respiratory Distress Syndrome (ARDS) in rodent models.
ARDS is a common complication associated with COVID-19 and is very often fatal, though mortality is commensurate with disease severity. For mild, moderate, and severe cases, the mortality rates are 27%, 32%, and 45%, respectively.
ARDS can be caused by what is known as cytokine storm, which is "a general term applied to maladaptive cytokine release in response to infection and other stimuli." In other words, cytokines (proteins that activate the immune system through chemical signaling) begin to overreact to an infection, which results in a surge of pro-inflammatory cytokines. This leads to severe inflammation that can damage healthy tissues. In the case of ARDS, the inflammation effects otherwise healthy tissues in the lungs.
What the researchers found was that THC inhibits pro-inflammatory cytokines and promotes anti-inflammatory cytokines by modulating microbial dysbiosis in the gut and lung biomes. "THC significantly increased the abundance of beneficial bacterial species, Ruminoccus gnavus, but decreased pathogenic microbiota, Akkermansia muciniphilia," they wrote.
As promising as these findings are, they do not mean that smoking marijuana will prevent COVID-19 or that cannabis somehow prevents the spread of coronavirus. However, should a patient with COVID-19 develop ARDS, THC may be helpful in reducing lung inflammation and thereby improve their prognosis.