While the EC50 value is clearly important for viral inhibition, the inhibiting n value is also of great importance. For example, if three inhibitors have the same EC50 value but different n values of 0.5, 1 and 2, then the C required for 99% inhibition will be 9801, 99, and 9.9 times the EC50 value, respectively. The inhibitor with n = 0.5 is much less effective than that with n = 1 or 2, and requires ~100-or 1000-fold higher C to achieve the same 99% inhibition, despite having the same EC50 value. Therefore, viable inhibitors should have n ≥ 1 (with n = 1 being the most widely observed) in order to achieve complete inhibition with a reasonable C. Whereas inhibitors with n < 1 are unlikely to become viable inhibitors because of difficulty to achieve complete inhibition. ) n ], for G13-CRD115 (red curves) and G13-CRD100 (black curves), where NI, C, IC50 and n are normalised infection (luciferase activity), concentration, concentration giving 50% inhibition, and inhibition coefficient, respectively. n = 1 was obtained for all fits and other fitting parameters are given in Table . The fit gave comparably low sub-nM EC50 values for both G13 -Tz-ECD100 and G13-Tz-CRD100, e.g. 0.25 ± 0.04 vs. 0.19 ± 0.02 nM (see SI, Fig. 2), indicating a high antiviral potency. However, the inhibition profile of G13-Tz-ECD100 gave n = 0.57 ± 0.06, meaning it is difficult to achieve complete inhibition. In contrast, the inhibition profile of G13-Tz-CRD100 yielded n = 1, meaning it can achieve complete viral inhibition by increasing C. This is evident from that, despite having similar sub-nM EC50 values, the normalized infection for G13-Tz-ECD100 is >3 fold that for G13-Tz-CRD100 at 3 nM (SI, Fig. .2). Therefore, presenting monomeric CRDs flexibly in a PNL, with each CRD serving as an independent binder, is key to potent, viable viral inhibition. This is because such flexible CRD binding units can readily adjust their relative positions to accommodate viral surface glycans and form strong multivalent binding.