HONG KONG: Using data from large scale genome-wide association studies, researchers from The University of Hong Kong's (HKUMed) School of Public Health and Faculty of Medicine from the Chinese University of Hong Kong discovered a causal link between smoking and a higher risk of contracting mild to severe COVID-19.
Previous observational research on smoking and COVID-19 risk have conflicting results, which could be due to confounding factors from lifestyle, such as obesity, or design biases, which are difficult to control in observational studies. However, more recent studies, including genetic studies, have indicated a possible link between smoking and severe COVID-19 risk. However, the association between smoking and milder forms of COVID-19, which account for most COVID-19 cases, remains unclear.
Researchers extracted smoking-related genetic variants from a previous genetic study, characterised by the lifetime smoking index, which captures smoking behaviour such as heaviness, duration, and initiation. They assessed their relationship with COVID-19 risk from extensive genetic summary data of genome-wide association studies.
According to the researchers, an increase in the lifetime smoking index, which indicates higher smoking behaviour throughout one's life, increases the probability of getting COVID-19 (both moderate and severe) by 19 per cent and severe COVID-19 by 48 per cent. On the other hand, lung function and COPD did not appear to be mediators in these relationships.
The study 'Association of smoking, lung function, and COPD in COVID-19 risk: A 2 step Mendelian randomisation study' has recently been published in Addiction.
