Figure 1.

In children, SARS-CoV-2-specific antibodies significantly increase through immunization. Anti-Spike S1 antibodies detected in serum of participants without a previous infection (A) or with a previous infection (B). A comparison between infected and non-infected participants after their first or second vaccine dose (C). Antibody levels were compared between participants 5-11 years of age and participants 12-17 years of age in previously infected participants 28 days after their first vaccination (D). The grey dots and lines for (A) and (B) represent median values. The horizontal lines for (C, D) indicate median values. Difference for panels (A–C) were investigated with a Kruskal-Wallis test with Dunn’s correction for multiple comparisons. Groups in panel (D) were compared with a Man-Whitney U test. ns, not significant; **, p < 0.01; ****, p < 0.0001; BAU, Binding antibody units.