Exploring genetic associations between allergic diseases and indicators of COVID-19 using mendelian randomization

We carried out a bidirectional Mendelian randomization (MR) including cases of eczema (N = 218,792), asthma (N = 462,933), and allergic rhinitis (N = 112,583). COVID-19 susceptibility (N = 1,683,768), COVID-19 hospitalization (N = 1,887,658), and COVID-19 severe respiratory symptom (N = 1,388,342) were sampled from GWAS database. The MR analysis was primarily based on inverse variance weighted (IVW), supplemented by several other algorithms. In the bidirectional MR analysis, eczema was negatively associated with COVID-19 susceptibility (odds ratio (OR)  = 0.92; p = 0.031) and COVID-19 hospitalization (OR = 0.81, p = 0.010); asthma was negatively associated with COVID-19 susceptibility (OR = 0.65, p = 0.005) and COVID-19 severe respiratory symptom (OR = 0.20, p = 0.001). No significant association was found between allergic rhinitis and COVID-19 susceptibility (OR = 0.80, p = 0.174), COVID-19 hospitalization (OR = 0.71, p = 0.207), or COVID-19 severe respiratory symptom (OR = 0.56; p = 0.167). The reverse MR analysis showed no potential reverse causal association. Our findings provided new evidence that allergic diseases might be associated with different risks of COVID-19 susceptibility, hospitalization, and severe respiratory symptom.