Amongst vaccinated donors, SARS-CoV-2-specific T cell responses, identified by measuring plasma-derived interferon-gamma (IFN-γ) following whole blood stimulation with SARS-CoV-2 peptides (as previously described refs. 14–18), and nucleocapsid (N)-binding IgG responses were elevated in those reporting prior infection, although both responses were highest in previously infected unvaccinated donors (Fig. 1a, b). This evidence concerns the gene IFNG and infection.