Tianjin Medical Journal ›› 2025, Vol. 53 ›› Issue (10): 1081-1086.doi: 10.11958/20251924

• Epidemiological Survey • Previous Articles     Next Articles

Epidemiological investigation on diphtheria serum IgG antibody levels in people aged 1-59 years old in Shaanxi province

ZHANG Chao1(), ZHOU Tiantian1, LI Siwen1, TANG Weijun2, HU Weijun1,()   

  1. 1 Shaanxi Provincial Center for Disease Control and Prevention, Xi’an 710054, China
    2 Hanzhong Center for Disease Control and Prevention
  • Received:2025-05-13 Revised:2025-07-03 Published:2025-10-15 Online:2025-10-12
  • Contact: E-mail:huweijun0828@163.com

Abstract:

Objective To investigate the serum diphtheria antibody levels in healthy people aged 1-59 years old in Shaanxi Province. Methods A stratified random sampling method was used to select healthy people aged 1-59 years old from 30 county-level disease surveillance sites in 10 cities of Shaanxi province from November to December 2017. Diphtheria IgG antibody was detected by enzyme-linked immunosorbent assay (ELISA), and the positive rate (IgG≥0.01 IU/mL) and mean geometric concentration (GMC) of diphtheria IgG antibody were analyzed. Results A total of 6 439 subjects completed laboratory testing. The positive rate and GMC of diphtheria IgG antibody were 85.79% and 0.035 (0.034-0.036) IU/mL, respectively. The GMC and the positive rate of diphtheria IgG antibody were higher in males than those in females (P<0.01). The positive rate of diphtheria IgG antibody in different cities was 65.25%-98.23%, and the GMC was 0.021 (0.018-0.024) IU/mL-0.046 (0.037-0.055) IU/mL, the difference between the groups was statistically significant (P<0.01). The GMC of the group with DCV immunization history, the group without DCV immunization history and the group with unknown DCV immunization history were 0.097 (0.090-0.105), 0.018 (0.018-0.019) and 0.027 (0.026-0.028) IU/mL, respectively, and the positive rates of diphtheria IgG antibody were 92.74%, 80.18% and 85.44%, respectively. There were significant differences between the three groups (P<0.01). Among the 9 age groups, the group with the lowest positive rate of diphtheria IgG antibody was the 40-49 age group (78.39%), and the highest was in the 1-2 age group (95.77%), which decreased with age (χ2=200.612, P<0.01). It showed a downward trend with age (χ2=200.612,P<0.01). The lowest GMC (IU/mL) was in the 40-49 age group [0.017 (0.016-0.017)], and the highest was in the 7-9 age group [0.190 (0.162-0.226)], showing a downward trend with increasing age (P<0.01). After the whole course of vaccination, the positive rate of diphtheria IgG antibody and the interval between the last dose of vaccination showed a downward trend (P<0.01). Conclusion The diphtheria immune barrier in whole population has been established in Shaanxi province, but the positive rate of diphtheria antibody and GMC in healthy people aged 1-59 years old show a downward trend with age.

Key words: diphtheria, immunoglobulin G, vaccination, Shaanxi, diphtheria-containing vaccines

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