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. Author manuscript; available in PMC: 2026 Jul 9.
Published in final edited form as: Vaccine. 2025 Jul 9;62:127476. doi: 10.1016/j.vaccine.2025.127476

Figure 2. Breakthrough infection post-boost elicits robust maternal anti-RBD antibody response and IgG4 subclass dominance.

Figure 2.

(A) Maternal RBD-specific IgG titers of longitudinal samples relative to days post first vaccination (DP1V) in Vaccinated/Uninfected before booster (light blue, n=398), Vaccinated/Uninfected after booster (dark blue, n=175), and Breakthrough Infection after booster (orange, n=90). The average days between first dose and booster was 269±50 days. The average days between first dose and infection was 332±114 days. (B) Post-booster comparison of maternal RBD-specific total IgG titers (limit of detection (LOD): dotted line) for Vaccinated/Uninfected (n=14) 259±19.7 days post booster (DPB) and Breakthrough Infection (n=15) 262.9±21.5 DPB. (C) Maternal RBD-specific IgG titers relative to days post initial antigen exposure (DPAE) via initial vaccination series or infection. (D) Subclass characterization of maternal RBD-specific IgG at delivery for Breakthrough Infection (left, n=24) and Unvaccinated/Infected (right, n=13). (E) Post-booster comparison of maternal RBD-specific IgG1 and IgG4 titers (LOD: dotted lines) for Vaccinated/Uninfected (n=14) 259±19.7 DPB and Breakthrough Infection (n=13) 262.9±21.5 DPB. (F) Maternal NP-specific IgG titers of longitudinal samples relative to days post infection (DPI) for Breakthrough Infection (orange, n=112) and Unvaccinated/Infected (red, n=32) cohorts. (G) Subclass characterization of maternal NP-specific IgG at delivery for Breakthrough Infection (left, n=24) and Unvaccinated/Infected (right, n=13).