Fig. 3: Surrogate SARS-CoV-2-neutralizing antibody assay (sVNT) in individuals who were naïve and previously infected following a single dose of the AZD1222 vaccine.
From: Immune responses to a single dose of the AZD1222/Covishield vaccine in health care workers
The sVNT titres (% of inhibition) were measured in naïve individuals (n = 68) (blue) and previously infected individuals (n = 26) (red) 28-32 days following the vaccine (A). The sVNT titres were correlated with the HAT titres for the WT virus (Spearman’s R = 0.71, p < 0.0001), B.1.1.7 (Spearman’s R = 0.67, p < 0.0001), B.1.351 (Spearman’s R = 0.51, p < 0.0001) and the SARS-CoV-2-specific total antibodies (Spearman’s R = 0.54, p < 0.0001) (B). The sVNT titres were correlated with the HAT titres for the WT virus (Spearman’s R = 0.64, p = 0.0005), B.1.1.7 (Spearman’s R = 0.73, p < 0.0001), B.1.351 (Spearman’s R = 0.25, p = 0.21) and the SARS-CoV-2-specific total antibodies (Spearman’s R = 0.56, p = 0.003) in previously infected individuals at baseline (C), and 28–32 days following a single dose of the vaccine for the WT virus (Spearman’s R = 0.47, p = 0.01), B.1.1.7 (Spearman’s R = 0.36, p = 0.06), B.1.351 (Spearman’s R = 0.13, p = 0.51) and the SARS-CoV-2-specific total antibodies (Spearman’s R = 0.25, p = 0.21) (D). The black dotted line indicates the positive cut-off for ACE2-blocking antibodies in A and for the HAT in B–D. The Wilcoxon matched-pairs signed-rank test was used to compare the means of the ACE-blocking antibodies (% of inhibition) before and after the vaccine. Spearman rank order correlation coefficient was used to evaluate the correlation between the HAT titres and the ACE-blocking antibodies. All tests were two sided. Data are presented as median values ± interquartile ranges as appropriate.
