ObjectiveTo investigate the antibody levels against diphtheria among healthy population in Jiading District of Shanghai, and to make evaluation of the effect of diphtheria toxoid vaccination strategy.

MethodsSerum samples were collected from healthy population in Jiading District of Shanghai in 2010-2013.Antibody against diphtheria was tested by the enzyme-linked immunosorbent assay (ELISA).Geometric mean titer (GMT) of diphtheria antibody was compared between different population characteristics.

ResultsA total of 1 029 serum samples were collected from the healthy population.With 1 003 of 1 029 diphtheria antibody titer of IgG (over 0.01 IU/mL), the positive rate was 97.47%, reaching the level of security protection (over 0.1 IU/mL) that accounted for 70.36%, and achieving the long-term protection level (over 1 IU/mL) that accounted for 35.57%;IgG GMT 0.325 IU/mL.There was significant difference in the positive rates and antibody levels between city residents and floating population in the field of diphtheria antibodies (χ²=4.708, P < 0.05;t=2.787, P < 0.05).There were statistically significant differences between different age groups in diphtheria antibody positive rates (χ²=30.262, P < 0.001) and statistically significant differences in GMT diphtheria antibody levels between different age groups (F=99.500, P < 0.001), GMT ranged in 0.029 IU/mL (30 years age group)~1.526 IU/mL (5 years age group).

ConclusionThe investigation of diphtheria antibody levels in Shanghai Jiading District truly reflects the effect of routine diphtheria immunization in Jiading District.DT (diphtheria & tetanus) vaccination for third grade junior is effective.We suggest a booster dose of diphtheria-containing vaccine for adolescents or adults so as to maintain immune levels.