[Review] Smoking and COVID-19: Rapid evidence review for the Royal College of Physicians, London (UK)

<jats:p>SARS-CoV-2 is the causative agent of COVID-19, an emergent zoonotic disease which has reached pandemic levels and is designated a public health emergency of international concern by the World Health Organisation. Early data suggest that older age, male sex and a diagnosis of hypertension or diabetes independently increase the risk of hospitalisation and death from COVID-19; however, the biological mechanisms underpinning these associations are currently unclear. The SARS-CoV-2 virus enters human cells through the ACE2 receptor. Current and past tobacco smoking is associated with changes in the ACE2 receptor expression, hypertension, diabetes and worse outcomes following other viral infections. It is hence plausible that smoking is an independent risk factor for hospitalisation and death from COVID-19. Here, we review available evidence for an association between smoking status and hospitalisation for COVID-19. We highlight concerns regarding the quality of available data and call for more systematic collection of smoking status in future studies.</jats:p>