PROS1 and infection: In a study found that the individuals with primary series vaccination with mRNA1273, or BNT162b2, or Ad26.COV2.S have similar median effector T cell reactivity (in terms of IFN-γ ELISpot spot forming units of SFU/106 PBMCs) against Omicron S-protein, as compared with that against WT SARS-CoV-2 (WT: 43, Omicron: 42), while prior infection could bring better performance (WT:311, Omicron:315 ).