IFNG and infection: We also noted that ∆3678-vaccination in mice with prior SARS-CoV-2 infection had stronger CD8+IFNγ+ T cell response in the lung, stronger CD4+IFNγ+ T cells and CD8+IFNγ+ T cells in the spleen, and stronger SARS-CoV-2- specific IgG2c responses in the sera compared to those without prior infection (Supplementary Fig. 1b–d).