MPO and COVID-19: Comparison of COVID-19 blood transcriptomic with IAV and RSV revealed that MPO, PRTN3, and PADI4 were selectively upregulated in coronavirus infections, SARS-CoV-1 and SARS-CoV-2, while TSHR and PTPRN2 autoantigens were distinctive to SARS-CoV-2 infection.