To validate this hypothesis, we evaluated responses to vaccination against the SARS-CoV-2 in PAD patients with different disease subtypes and clinical manifestations using a validated interferon-gamma release assay (IGRA) that measures the release of IFN-γ by peripheral blood mononuclear cells stimulated in vitro with the SARS-CoV-2 S (spike) 1 protein (19, 20). This evidence concerns the gene IFNG and peripheral arterial disease.