Fig. 4. Increase in MERS-CoV neutralizing antibodies after booster vaccination.

MERS-CoV neutralization was measured by a ≥80% plaque reduction neutralization test (PRNT₈₀) and b, c virus neutralization test (VNT). Neutralizing antibody levels were measured in reciprocal titers (y-axes) at multiple timepoints after first (Day (D) 0 (D0), D35, D42, D84, and D180) and booster (B) (B:D0, B:D7, B:D14, and B:D28) vaccinations (x-axes). Arrows indicate vaccinations. Horizontal dashed lines indicate the cut-off levels for positivity. a+b Boxes indicate 25–75 percentile; whiskers are min. to max.; medians are shown as horizonal lines within the boxes. Former low dose (LD, n = 3) and high dose (HD, n = 7) vaccinees are depicted in blue and red, respectively, controls in gray (n = 4). c VNT titers after prime vaccination measured longitudinally in the five individuals who did not develop nAb after prime vaccinations. Source data are provided as a Source Data file.