IFNG and infection: IFN-γ+ N-SARS-CoV-2-specific T cell frequencies also declined at 10 months upon infection in adults compared to earlier time points (6.1 SFU/2.105 PBMCs at T4 vs 60 (P<0.0001), 37.8 (P=0.0002), and 29.6 (P=0.037) SFU/per 2.105 PBMCs at T1, T2, and T3, respectively), but remained significantly higher compared to unexposed adults (0.05 SFU/2.105 PBMCs) (Figure 6B, right panel).