Table 2.
Age Group, y | DT Ab Titer, Mean (SD), IU/mL |
DT Ab Half-life (95% CI), y |
TT Ab Titer, Mean (SD), IU/mL |
TT Ab Half-life (95% CI), y |
||
---|---|---|---|---|---|---|
Cross-sectional | Longitudinal | Cross-sectional | Longitudinal | |||
<50 | 0.43 (0.70) | 24 (12–∞) | 19 (15–25) | 4.16 (5.41) | 11 (8–20) | 11 (10–13) |
≥50 | 0.28 (0.48) | 30 (18–84) | 21 (15–34) | 3.05 (3.62) | 14 (11–20) | 15 (11–24) |
Abbreviations: Ab, antibody; CI, confidence interval; DT, diphtheria toxin; SD, standard deviation; TT, tetanus toxin.
a Antibody titers to DT or TT were determined after stratifying the cohort of 540 subjects of known age into age groups of <50 or ≥50 years (both n = 270). Antibody half-life estimates (in years) were determined after stratifying 388 subjects of known age and estimated time after vaccination into age groups of <50 (n = 177) or ≥50 (n = 211) years. Longitudinal data [7] were stratified by age for comparison with the cross-sectional analysis.