In the search for aptamers targeting COVID-19, Schmitz et al. [7] used lambda digestion to create their ssDNA selection pool for the isolation of aptamer targeting the SARS-CoV-2 S protein, while Song et al. [4] used the streptavidin-coated beads to separate the desired sequence from the biotinylated sequence during the isolation of aptamer targeting the SARS-CoV-2 SRBD protein. Here, PROS1 is linked to COVID-19.