FIG. 5.

Effect of addition of human fH (25 μg/ml) on group C serum bactericidal titers measured with infant rabbit complement. The postimmunization sera were from 11 adults given a group C meningococcal conjugate vaccine or 19 children, aged 4 to 5 years, immunized with quadrivalent meningococcal polysaccharide vaccine (see Materials and Methods). The differences between the respective geometric mean titers (GMT) in human vaccinee sera measured using rabbit complement in the absence or presence of human fH were significant (P < 0.01). CI, confidence interval.