Fig. 3

The prevalence of anti-tetanus toxoid antibody and geometric mean titers (GMTs) in the study population. The x-axis represents the five age groups and the sample size in each age group. The scale on the right represents the proportion (%) of the population with positive anti-tetanus toxoid antibody. The scale on the left represents the GMTs in each age group with the means indicated as a red line. Antibody measurements were negative (white), 0.1to < 0.5 IU/ml (light blue), 0.5 to < 1.1 IU/ml (blue), 1.1 to < 5 IU/ml (dark blue), and > 5 IU/ml (black)