Accurate affinity profiling of a SARS-CoV-2 antibody in serum

The ability to accurately characterize the immune response against SARS-CoV-2 is of vital importance in managing the current COVID-19 pandemic. Measuring antibody affinity under physiologically relevant conditions in complex mixtures like serum remains challenging but is critically important to furthering our understanding of the immune response and protection window in patients and vaccinated individuals. Using Microfluidic Diffusional Sizing (MDS), we have characterized an anti-spike S1 antibody by measuring its binding affinity to the receptor binding domain (RBD) of the SARS-CoV-2 spike protein directly in serum.