Correlations between anti-PT IgG and PT-neutralizing antibody titers among young children, older children, and adults.

<p>Anti-PT IgG titers in individual serum samples (x-axis in log scale) were plotted against PT-neutralizing antibody titers (y-axis). Values on the y-axis indicate the reciprocal serum dilution required to neutralize PT activity. The age groups were 4–7 years, 10–14 years, and 35–44 years. r_s, Spearman’s rank correlation coefficient; Y, years.