In the past weeks the question has been raised in social media and news sites whether the use of medical cannabis for the lung disease, COVID-19, can have medicinal benefits. Indeed, research is currently pursuing interesting approaches.
What is COVID-19?
COVID-19 is the name given to the lung disease caused by the coronavirus Sars-CoV-2. This is a novel virus closely related to the Sars virus (Sars-SoV), which first appeared last year at a Chinese market in the city of Wuhan. It is not yet known where the virus originally came from. However, bats and flying foxes are considered the possible reservoir of the virus.
Sars-CoV-2 virus is spread by droplet infection, i.e. when speaking or coughing. How long the virus survives on different surfaces is still unclear as this depends on various factors, such as the type of surface, humidity or temperature, the virus could survive for a few hours, but also for a few days. However, the authorities estimate the probability of a person infected with Sars-CoV-2 contaminating surfaces as low.
Incubation period and symptoms
The period between infection and the onset of symptoms (incubation period) is 2 to 14 days for the Sars-CoV-2 virus. The symptoms are non-specific and can manifest themselves in the form of a dry cough, fever and breathing problems. In addition, many affected people report a temporary loss of their sense of smell and taste.
Some infected people show no symptoms at all, while others suffer from mild cold-like symptoms such as sore throat and chills. Occasionally those affected may also suffer from headaches and diarrhoea.
According to the World Health Organization (WHO) and the Robert Koch Institute, about 80% of cases are mild. Around 14% of those affected develop severe symptoms such as shortness of breath and pneumonia. Roughly 5% develop a life-threatening condition which can include septic shock, respiratory arrest or multiple organ failure.
Elderly people are particularly at risk, but also people with the following pre-existing conditions:
- Respiratory diseases
- High blood pressure
- Cardiovascular diseases
Research on medical cannabis and COVID-19
Researchers from the Canadian University of Lethbridge explain in their preprint study that the cannabinoids THC and CBD may be able to prevent the spread of the virus from entering the cells in the lungs. 
The study states that Sars CoV-2 virus needs the ACE2 receptor to enter the human host cell. This receptor is not only found in the lung tissue, but also in the kidneys, gastrointestinal tract, testes, and mouth and nose mucus.
In their theory, the researchers assume that the cannabinoids might alter ACE2. Put simply, this means If there’s no ACE2 in the tissue, the virus can’t get in. As a result, the human host would be less susceptible to the virus, which might reduce the risk of infection.
Researchers point to cannabis variants with high CBD content
The Canadian researchers point in particular to their self-developed cannabis variants with a high CBD content, as various studies have shown that CBD can have anti-inflammatory effects. Furthermore, according to a media report, the researchers explain that the extracts from their cannabis line could be an additional therapy for the treatment of COVID-19. However, there are no meaningful studies to date that could support or invalidate this theory. 
Israeli researchers plan CBD study
Researchers at the University of Tel Aviv are now planning to conduct clinical trials. These will investigate the efficacy of CBD-enriched exosomes for inhalation on the lung disease COVID-19. Due to its anti-inflammatory and immunoregulatory properties, CBD could help to repair the damaged cells in the lung through a synergistic effect. 
In a further investigation, the researchers will administer a combination of CBD and steroids to COVID-19 patients, as they believe that CBD may possibly enhance the effect of the steroids.
Since medical cannabis has a broad spectrum of effects, it is not surprising that researchers are now also looking into the use of medical cannabis in COVID-19. As mentioned, interesting approaches are being pursued here, which will prompt further researchers to carry out studies and investigations.
 University of Lethbridge, Kovalchuk et al., 2020, “In Search of Preventative Strategies: Novel Anti-Inflammatory High-CBD Cannabis Sativa Extracts Modulate ACE2 Expression in COVID-19 Gateway Tissues”
 PraxisVita, Miriam Mueller-Stahl, 2020, “Corona-Studien: Cannabis schützend oder schädlich?”