It is therefore conceivable that the use of a JAKi with preferential selectivity for JAK1, which therefore has a predominantly anti-inflammatory action and does not inhibit kinases involved in response to infections and tumours (JAK3) or the production of platelets and other blood cells (JAK2) may be associated with a better safety profile than the pan-inhibitor tofacitinib. This evidence concerns the gene JAK3 and infection.