Even though 16 of these patients tested negative for neutralizing antibodies after 12 months, 94% (15/16) exhibited SARS-CoV-2 T-cell immune response including IFN-γ [50], matching the results from another study examining mild COVID-19 and the persistence of symptoms and immune response 12 months post-infection, where two-thirds of the patients presented specific IFNγ-producing T-cells [51]. This evidence concerns the gene IFNG and infection.