AHR and COVID-19: To elucidate the inverse relationship between smoking and COVID-19 risk, several hypotheses have been posited: one suggests that smoking could activate the aryl-hydrocarbon receptor (AHR), possibly suppressing the angiotensin-converting enzyme 2 (ACE2) receptor which the virus uses for cellular entry [9]; another underscores the potential of nicotine to modulate inflammation [10, 11]; and yet another speculates on nitric oxide’s toxic influence on the virus [12].