Figure 4. Longevity of the nAb response.

a) ID₅₀ at peak neutralization (measured using HIV-1 based virus particles, pseudotyped with SARS-CoV-2 S) is plotted against the donor matched ID₅₀ at the last time point sera was collected. Only individuals where the peak ID₅₀ occurs before the last time point, and where the last time point is >30 days POS are included in this analysis. The dotted line represents the cut-off for the pseudovirus neutralization assay. b-c) EC₅₀ values for IgG binding to S, RBD and N were calculated at time points with peak ID₅₀ and the final time point sera was collected. EC₅₀ at peak neutralization is plotted with the donor matched EC₅₀ at the last time point sera was collected. Individuals with a disease severity 0-3 are shown in black and those with 4/5 are shown in red. The dotted line represents the cut-off for EC₅₀ measurement. e) Correlation of ID₅₀ with IgG EC₅₀ against S (r ²=0.8293), RBD (r ²=0.7128) and N (r ²=0.4856) (Spearman correlation, r. A linear regression was used to calculate the goodness of fit, r ²). f) Change in IgG EC₅₀ measured against S, RBD and N and ID₅₀ using pseudovirus and wild type virus over time for 4 example patients (all severity 4). The lowest dilution used for the pseudovirus and wild-type virus neutralization assays are 1:50 and 1:20 respectively.