Figure 3. Second dose of vaccination is required for boost in functional antibody response in serum and breastmilk of lactating women.

A. A PCA was built on LASSO-selected SARS-CoV-2-specific features from samples collected post-prime vaccination (n = 28) (purple) and from samples collected post-boost vaccination (n = 13) (blue) in lactating women. The ellipses represent the 95% confidence interval for each group. The heatmaps show the contribution of each feature along each principal component (PC). The color of the heatmap indicates in which group each feature is enriched. Blue indicates that all features were enriched post-boost.

B. A PCA was built on LASSO-selected SARS-CoV-2-specific features in breastmilk samples collected post-prime vaccination (purple) or post-boost vaccination (blue), using timepoint as the outcome variable. The ellipses represent the 95% confidence interval for each timepoint. The heatmap shows the contribution of each feature to the corresponding PC.

C. The polar plots show the mean percentile rank for each feature for post-prime or post-boost samples in the serum of lactating women.

D. The polar plots show the mean percentile rank for each feature for post-prime or post-boost samples in breastmilk.

E. The dot plot shows the transfer ratio of breastmilk:serum for each isotype (left) and FcR (right) measured 3 to four weeks post-prime vaccination. Horizontal dotted lines indicate a transfer ratio of 1. Horizontal bars indicate median. Significance was determined by a one-way ANOVA followed by Tukey’s multiple comparison correction. * p <0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.

F. The dot plot shows the transfer ratio of breastmilk:serum for each isotype (left) and FcR (right) measured 2 to 5.5 weeks post-boost vaccination. Horizontal dotted lines indicate a transfer ratio of 1. Horizontal bars indicate median. Significance was determined by a one-way ANOVA followed by Tukey’s multiple comparison correction. ** p < 0.01,*** p < 0.001.

G. The dot plots show the transfer ratio of breastmilk:serum between ADCP and ADNP measured post-prime vaccination. The horizontal dotted line indicates a transfer ratio of 1. Horizontal bars indicate median. Significance was determined by Wilcoxon-matched pairs signed rank test. No significant difference was observed.

H. The dot plots show the transfer ratio of breastmilk:serum between ADCP and ADNP measured post-boost vaccination. The horizontal dotted line indicates a transfer ratio of 1. Horizontal bars indicate median. Significance was determined by Wilcoxon-matched pairs signed rank test. p < 0.001.