Rs34536443 is a loss-of-function missense variant (p.Pro1104Ala) for TYK2 and the functionally impairing minor C allele was associated with a 50% increased risk for severe COVID-19 (odds ratio: 1.50; 95%-CI: 1.40– 1.62, p-value = 4.3 x 10−29) but a 23% reduced risk for rheumatoid arthritis (odds ratio: 0.77; 95%-CI: 0.72–0.83; p-value = 2.4 x 10−12) as well as other autoimmune diseases, in particular psoriasis (Supplementary Data 8). Here, TYK2 is linked to rheumatoid arthritis.