DPP9 and COVID-19: The association between OAS1/2/3 variant and pneumonia development was statistically significant after adjusting for the main genetic factors known to predispose to severe COVID-19: LZTFL1 and DPP9 variants, and remained significant also after adjusting for the main clinical risk factors identified in children cohort (presence of chronic diseases and prematurity) (OR 3.28, 95% CI 1–10.7; p-value 0.049).