Seroepidemiology of Tetanus among Healthy People Aged 1–59 Years Old in Shaanxi Province, China

The study aims to determine the seroprevalence of antibodies against tetanus among healthy people aged 1–59 years old in Shaanxi province. IgG against tetanus in serum samples were detected by ELISA. 6,439 subjects were enrolled. The positive rate (≥0.01 IU/mL) was 84.39% and GMC was 0.03 IU/mL. There were significant differences in positive rates (χ(2) = 308.944, p < 0.01) and GMC (Z = 5,200,000, p < 0.01) among different age groups. The positive rates (χ(2) = 304.3, p < 0.01) and GMCs (χ(2) = 146.417, p < 0.01) showed regional differences. Both full protection rate (≥0.1 IU/mL) (χ(2) = 36.834, p < 0.01) and GMC (Z = 688,000, p < 0.01) increased with the doses of tetanus-toxoid-containing vaccines (TTCVs) administered. The positive rate (χ(2) = 54.136, p < 0.01) and GMC (Z = 140,200, p < 0.01) decreased gradually with the time interval after full immunization with TTCVs. The full protection rate (≥0.1 IU/mL) (χ(2) = 176.201, p < 0.01) and GMC (Z = 629,900, p < 0.01) decreased with the interval (years) since the last dose of TTCVs. There were significant differences in the positive rates and GMCs for different ages, regions, immunization histories of TTCVs, and doses of TTCVs administered. The full protection rate and GMC decreased with the interval following full immunization with TTCVs and the interval since the last dose of TTCVs. The importance of using tetanus booster doses should be emphasized in adolescents and adults.