Fig. 4: Longevity of the neutralizing antibody response.

a, ID₅₀ at peak neutralization (measured using HIV-1-based viral particles, pseudotyped with the S glycoprotein of SARS-CoV-2) is plotted with the donor-matched ID₅₀ at the last timepoint from which serum was collected. Only individuals in whom the peak ID₅₀ occurs before the last timepoint and the last timepoint is >30 d POS are included in this analysis (n = 35). The dotted line represents the cut-off for the pseudovirus neutralization assay. b–d, EC₅₀ values for IgG binding to S glycoprotein (b), RBD (c) and N protein (d) were calculated at timepoints with peak ID₅₀ and the final timepoint sera were collected. EC₅₀ at peak neutralization is plotted with the donor-matched EC₅₀ at the last timepoint sera were collected. Individuals with a disease severity 0–3 are shown in black and those with 4/5 in red. The dotted line represents the cut-off for EC₅₀ measurement. The ELISAs to determine EC₅₀ values were conducted once. e, Correlation of ID₅₀ with IgG EC₅₀ against S glycoprotein (r² = 0.7924), RBD (r² = 0.6781) and N protein (r² = 0.4533) (Spearman’s correlation, r; a linear regression was used to calculate the goodness of fit, r²). f, Change in IgG EC₅₀ measured against S glycoprotein, RBD and N protein, and ID₅₀ using pseudovirus and wild-type virus over time for four example patients (all disease severity 4). The lowest dilution used for the pseudovirus and wild-type virus neutralization assays are 1:50 and 1:20, respectively.