The anti-SARS CoV-2 S-protein IgG and anti-N-protein IgG and anti-N protein IgA were measured in forty patients on day of RT-PCR within 7 days post onset of COVID-19 symptoms (POCS) and in twenty five patients at follow-up sera sampling on day 19 to day 27 of POCS. Here, PROS1 is linked to COVID-19.