Fig. 1: Robust IgG responses toward ancestral and Delta RBD in FN and NI cohorts after mRNA vaccine vaccination.
a, Study and experimental design of the COVAC cohort in which blood samples were collected from 58 FN and 39 NI individuals. S, spike protein. b, Age and sex distribution of COVAC participants as in a (nFN = 58, nNI = 39). c, ELISA of RBD IgG showing the titration curves of absorbance (450 nm). The orange dashed lines indicate the endpoint titer cutoffs. d,e, ELISA showing ancestral RBD IgG at V1, V1a, V2, V3 and V4 (FN: nV1 = 38, nV1a = 18, nV2 = 37, nV3 = 46, nV4 = 26, V1 versus V1a P = 0.0171; NI: nV1 = 33, nV1a,V4 = 31, nV2 = 38, nV3 = 39, V3 FN versus NI P = 0.0013) (d) and V5 (nV5 = 10; V1 versus V5, P = 0.0078; V4 versus V5, P = 0.0078) (e). f, Seroconversion rate (%) of ancestral RBD IgG (FN: nV1a = 13, nV2 = 17, nV3 = 26, nV4 = 16; NI: nV1a = 29, nV2 = 32, nV3 = 33, nV4 = 27) defined as at least a fourfold increase in log10-transformed titer compared to V1. g,h, ELISA showing the Delta and Omicron RBD IgG at V1, V3 (FN: nV1 = 32, nV3 = 37 (Delta), nV3 = 38 (Omicron); NI: nV1 = 33, nV3 = 39; V3 FN versus NI, P = 0.0013 (ancestral) and P = 0.0056 (Delta)) (g) and V5 (nV5 = 10; V1 versus V5 P = 0.0078 (Delta, Omicron)) (h). i, Spearman correlations between V3 ancestral RBD IgG and V3 Delta or Omicron RBD IgG (FN: nDelta = 38 and nOmicron = 39; NI, n = 39). j, Microneutralization assay showing neutralizing antibodies against ancestral and Delta SARS-CoV-2 at V1, V3 and V4 (FN: nV1 = 31, nV3 = 38, nV4 = 8; NI: nV1 = 33, nV3 = 39, nV4 = 11, NI V1 versus V4, P = 0.0078 (ancestral)). The bars indicate the median with the interquartile range (IQR). The black horizontal dotted lines indicate seropositivity. Statistical significance was determined with a two-sided Wilcoxon test in each cohort or a two-sided Mann–Whitney U-test between FN and NI cohorts. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.
