Besides, embedded on the viral surfaceas a homotrimer, the S-protein is probably more accessible for theaffinity-based assay.14,15 So far, S-protein-targeting affinityelements used in SARS-CoV-2 detection include antibodies and theirfragments,16,17 DNA aptamer,18,19 nanobodies,20 peptides,21−23 and ACE2 receptor analogue mini-proteins.24,25 Among these affinity elements, peptides demonstrate good chemicalstability, processability, and scalability, making them promisingcandidates as the affinity elements for the development of sensitiveand user-friendly household COVID-19 immunoassays. Here, PROS1 is linked to COVID-19.