Mean Anti-Hib Antibody Concentrations and Percentage of Participants with Protective Levels.

<p>Only 20% of children under 5 years old have protective (>0.15 µg/ml) antibody levels, rising to 83% of 15–54 year-olds. Geometric mean anti-polyribosylribitol phosphate IgG concentrations for each age group are plotted on the left y-axis (±SE). The percentage of participants with antibody concentrations >0.15 µg/ml (‘short-term protection’: the height of the entire column) and >1 µg/ml (‘long-term’ protection: the height of only the shaded column) are plotted on the right y-axis (±SE). Sample sizes (n): Cord Blood (n = 15); 0.5–4 yrs (n = 15); 5–7 yrs (n = 15); 8–14 yrs (n = 18); 15–54 yrs (n = 12); 55–77 yrs (n = 11).</p