CD4 and Crohn disease: Here, it was observed that Infliximab therapy regulated the Crohn’s disease, as twin 2 did not present any signal or symptoms of gut inflammation during COVID-19 vaccination, and the presence of Infliximab may have a role in the reduction/delayed of central memory CD4+ T cells, CD4+ Th1, and Th2 responses, as well as in the absence of specific IgG antibody production and memory B cell activation compared to the healthy twin (twin 1).