Fig. 4

Association of IgG levels at M24 with post-M24 breakthrough infections. a IgG levels (MFI) at month (M)24 against the receptor-binding domain (RBD) of Wuhan SARS-CoV-2 Spike glycoprotein (S), S, its subunits S1 and S2, and against the nucleocapsid (N), in breakthrough infected (n = 95) and non-breakthrough infected (n = 274) individuals. b IgG levels (MFI) at M24 against Delta and Omicron BA.1 S. The center line on each box corresponds to the median MFI, the lower and upper hinges correspond to the first and third quartiles, and the whiskers extend from the hinge to the highest or lowest value within 1·5 × IQR of the respective hinge. Statistical significance was tested by Wilcoxon rank-sum test and adjusted for multiple comparisons using Benjamini–Hochberg method