In a new study conducted by researchers at Washington University School of Medicine in St. Louis, it has been found that cannabis use is associated with an elevated risk of serious illness for individuals infected with COVID-19. The study, published in JAMA Network Open, analyzed the health records of 72,501 COVID-19 patients from a major Midwestern health-care system during the first two years of the pandemic.

The researchers discovered that individuals who reported using cannabis at least once in the year prior to developing COVID-19 were significantly more likely to require hospitalization and intensive care compared to those who did not use the drug. This increased risk was found to be similar to the risk associated with smoking.

Senior author of the study, Li-Shiun Chen, emphasized that the perception of cannabis as being safe and potentially beneficial for health may be misguided, as there has been limited research on its health effects compared to tobacco and alcohol. Individuals who admitted to current cannabis use, regardless of frequency, were shown to have a higher likelihood of needing hospitalization and intensive care when infected with COVID-19.

However, an interesting finding from the study was that while smokers had a significantly higher risk of death from COVID-19 compared to nonsmokers, the same was not true for cannabis users. Chen noted that more evidence is needed to fully understand the relationship between cannabis use and mortality risk.

The study analyzed anonymized electronic health records of COVID-19 patients seen at BJC HealthCare hospitals and clinics in Missouri and Illinois between February 2020 and January 2022. Demographic data, medical conditions, substance use, and outcomes of the illness were assessed, including hospitalization, admission to the intensive care unit (ICU), and survival rates.

COVID-19 patients who reported cannabis use within the previous year were found to be 80% more likely to be hospitalized and 27% more likely to be admitted to the ICU compared to non-users, after accounting for factors such as tobacco smoking, vaccination, other health conditions, date of diagnosis, and demographics. In comparison, tobacco smokers with COVID-19 had a 72% higher risk of hospitalization and a 22% higher risk of requiring intensive care.

The study's findings contradict previous research suggesting that cannabis may have therapeutic effects against viral diseases like COVID-19. Chen highlighted that while previous studies often focused on cell or animal models, the strength of their research lies in its use of real-world healthcare data, providing reliable outcomes.

The researchers cautioned that the study was not designed to determine why cannabis use might exacerbate COVID-19 symptoms. It is speculated that the inhalation of marijuana smoke could potentially harm lung tissue, leaving it more vulnerable to infection, similar to the effects of tobacco smoke. Additionally, cannabis is known to suppress the immune system, which could hinder the body's ability to fight off viral infections regardless of the method of consumption.

First author Nicholas Griffith, a medical resident at Washington University, expressed the need for further research to determine the safety and effects of different modes of cannabis consumption, such as edibles. While the study establishes a link between cannabis use and increased severity of COVID-19, it does not provide insights into the specific dosage or consumption method that may influence the outcome.

The study's results contribute to the growing body of evidence on the potential risks associated with cannabis use and emphasize the importance of further research to fully understand its impact on health, particularly in the context of COVID-19.