Fig. 1.

MPXV-specific antibodies (IgG) and MPXV-specific neutralizing antibodies (nAbs) response in smallpox vaccine experienced (red plot) vs. smallpox vaccine-naïve (black plot) Panel A. Titers of MPXV-specific IgG were measured by immunofluorescence (1:20) starting dilution. Intra-group comparisons were performed with paired t-test; inter-group comparisons with unpaired t-test. Panel B. Titers of MPXV-specific nAbs were measured by 50% plaque reduction neutralization test (1:10 starting dilution). Intra-group comparisons were performed with paired t-test, and inter-group comparisons with unpaired t-test. Titers are expressed as Geometric Mean Titres (GMT) of the reciprocal serum dilution (log₂ scale). Error bars refer to the 95% confidence interval of GMT. ∗∗∗∗p < 0.0001.