Particularly in severe COVID-19 patients, higher frequencies of SARS-CoV-2-specific IFN-γ+CD69+CD4+ T cells, with a high expression of Cytotoxic T-Lymphocyte-associated Protein 4 (CTLA-4), were observed as compared to uninfected and convalescent patients [15]. This evidence concerns the gene CTLA4 and COVID-19.