MUC5B and pulmonary fibrosis: Located in the enhancer region of the MUC5B, rs35705950, is a known risk factor for IPF, and a high mortality rate was observed among the COVID-19 patients with pre-existing IPF.24 However, the variant is associated with a reduced risk of severe COVID-19 (OR=0.89), revealing the risk allele’s opposing effect for infection and pulmonary fibrosis.