IFNG and infection: In rhesus macaques, the IFN-γ SFU measured following stimulation with spike protein peptide megapools (MP) 1–3 did not differ significantly between animals euthanised at either the day 4–5 (early) or the day 14–19 (late) post-infection time-point in comparison to SFU frequencies measured in the naïve control animals.