The lungs of people who smoke may contain more of the receptors that the new coronavirus uses to invade cells. This could explain why people with the virus who also smoke appear to be particularly vulnerable to severe illness.
The majority of people who acquire SARS-CoV-2, the virus that causes COVID-19, experience mild-to-moderate symptoms and will fully recover without hospital treatment.
However, several studies suggest that people who smoke are significantly more likely than people who do not to develop a severe form of the illness.
For example, according to a recent study of COVID-19 cases in hospitals in mainland China, 11.8% of people who smoked had a nonsevere form of the disease, while 16.9% had severe disease.