Underscoring the importance of T cells, earlier reports revealed that CD4+ and CD8+ T-cell responses against the Spike (S), Membrane (M), and Nucleocapsid (N) proteins of original SARS-CoV persisted for up to 11 years post infection (11) and N-specific T-cell reactivity to 17 years post infection (12). This evidence concerns the gene CD4 and infection.