PTGER3 and COVID-19: Proteins with the highest levels of immunogenicity in COVID-19 patients were proteins N, S1, and S2 (median: 7825, 4098, and 1789 MFI, respectively) as well as their respective sub-fragments N-EP3, S1-RBD, and S2′ (median: 2943, 4228, and 1030 MFI, respectively) (Figure 2A).