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. Author manuscript; available in PMC: 2023 Sep 19.
Published in final edited form as: Vaccine. 2013 Jul 13;31(42):4917–4922. doi: 10.1016/j.vaccine.2013.07.015

Table 2.

Population immunity by diphtheria antibody concentrationa and age group, Tajikistan, 2010.

Variables Tested, No. Seronegative (<0.1 IU/mL)
 Seropositive (≥0.1 IU/mL)
<0.01 IU/mL
 0.01–0.09 IU/mL
 0.1–0.99 IU/mL
 ≥1.0 IU/mL
No. % 95% CI No. % 95% CI No. % 95% CI No. % 95% CI
Overall 2325 502 22.4 19.1–26.0 598 26.2 24.3–28.2 808 34.7 31.1–38.5 417 16.7 14.4–19.3
By age group
1–2 years 208 26 12.9 8.8–18.4 46 22.1 15.7–30.1 75 38.1 32.9–43.5 61 26.9 20.1–35.1
3–6 years 422 75 17.8 13.1–23.6 99 24.0 20.1–28.5 149 34.9 30.0–40.1 99 23.3 19.7–27.4
7–9 years 272 56 21.7 14.9–30.4 42 15.7 11.2–21.6 73 26.8 21.1–33.4 101 35.8 28.9–43.4
10–14 years 514 173 35.5 29.9–41.4 140 27.4 23.4–31.9 134 25.0 20.4–30.2 67 12.1 7.7–18.7
15–19 years 475 136 29.3 24.1–35.1 165 35.4 32.1–39.0 145 29.5 24.3–35.3 29 5.8 3.8– 8.7
20–24 years 434 36 8.1 5.4–12.0 106 24.1 20.7–27.9 232 54.4 49.1–59.6 60 13.4 10.1–17.4
a

An antibody concentration of 0.01 IU/mL is the lowest level giving some degree of protection for diphtheria, concentrations ≥0.1 IU/mL are considered a fully protective level of circulating antibodies; antibody concentrations of ≥1.0 IU/mL are associated with long term protection [10].