Paradoxical findings on smoking in reduced risk of severe COVID-19

We read with interest the paper by Gaoet al. exploring the relationship between cigarettes, e-cigarette use and severe COVID-19 risk using the QResearch database in England, where they found an association of current smoking in reduced risk of severe COVID-19.1 Inverse association of smoking in severe COVID-19 risk has also been reported in previous observational studies using large data-linkage records such as the OpenSAFELY study,2 although other observational studies and Mendelian randomization studies showed a positive association with severe COVID-19 risk.3 –5
Source: International Journal of Epidemiology - Category: Epidemiology Source Type: research