Among them, the site and the route of injection, older age, obesity, renal failure, immunodeficiency and certain HLA types, particularly homozygosity for HLA-DRB1 * 0301 and HLA-DRB1 * 0701, have been associated with lack of immunogenicity [101,102,103]. This evidence concerns the gene HLA-DRB1 and Immunodeficiency.