There's a good chance this comes down to nicotine.
> Biological mechanisms exist to explain why smoking could protect from SARS-CoV-2 infection. I don’t pretend to be qualified to assess them, but the basic idea is that nicotine competes with the virus for the ACE2 receptor. The few studies looking at vaping have produced mixed results, but an intriguing study from the US found that Covid-19 patients who are smokers had better outcomes in hospital when given nicotine patches.
> Biological mechanisms exist to explain why smoking could protect from SARS-CoV-2 infection. I don’t pretend to be qualified to assess them, but the basic idea is that nicotine competes with the virus for the ACE2 receptor. The few studies looking at vaping have produced mixed results, but an intriguing study from the US found that Covid-19 patients who are smokers had better outcomes in hospital when given nicotine patches.