a, Pseudotyped virus IC50 values of VH binders. The neutralization potency improves when VH domains are engineered into multivalent and bi-paratopic constructs. b, Correlation of in vitro binding affinity (Kd) and pseudotyped virus neutralization (IC50) of VH binders. Data were fit to a log–log linear extrapolation. c, Pseudotyped virus neutralization curves of multi-site VH2 in comparison to single-site VH2 demonstrate that the multi-site VH2 have a more cooperative neutralization curve. d, Pseudotyped virus neutralization curves of mono-, bi- and trivalent formats of VH B01, demonstrating the potency gains driven by valency. e, Authentic SARS-CoV-2 neutralization curves for the most potent VH formats were determined via quantitative polymerase chain reaction (qPCR) of the viral genome in cellular RNA. All pseudoviral neutralization data were repeated as n = 2 independent replicates. Authentic virus neutralization data were repeated as n = 2 independent replicates. Data represent the average and standard deviation of replicates.