“…some genes associated with the risk of developing severe COVID appear to lower the risk of certain autoimmune diseases. For now, why that might be remains a mystery.

 Verma A., et al., A Phenome-Wide Association Study of genes associated with COVID-19 severity reveals shared genetics with complex diseases in the Million Veteran Program.
PLoS Genet. 2022 Apr; 18(4): e1010113. Published online 2022 Apr 28. doi: 10.1371/journal.pgen.1010113

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9049369/

“…While genetic variants associated with severe COVID-19 were also associated with known risk factors and poor outcomes related to COVID-19 such as deep venous thrombosis, a large subset of these variants were also associated with reduced risk of conditions largely comprised of immune-mediated diseases, e.g., psoriasis, lupus, rheumatoid arthritis. With regards to the latter, the shared genetic architecture between COVID-19 and immune-mediated conditions suggests that pathways controlling both immune tolerance and immunodeficiency are important for COVID-19 severity, with implications when considering targeting these pathways for treatment. …”