A Two-Step Mendelian Randomization Involving Chronic Obstructive Pulmonary Disease, COVID-19 and Risk Factors.

There exists strong genetic evidence linking environmental factors, smoking and lung function, and COVID-19's severity. Mild COVID-19 is also captured, but to a lesser extent, through minimal evidence. Low lung function exacerbates COPD but does not mediate the implications of smoking on the risk of COVID-19. Our study has implications in the public health policy and messaging for smokers and risks of COVID-19.