The evaluation of anti-diphtheria toxoid antibodies in healthy population in Kon Tum, Vietnam: a population-based study

•The risk of diphtheria remains high in Kon Tum given the low seroprevalence.•One third of community in Kon Tum have no protective antibodies to diphtheria.•The antibodies from previous childhood vaccination gradually wane over time.•A booster dose (5-7 years) is recommended for adolescents and adults in Vietnam. Despite diphtheria immunization are to apply an effective primary immunization in childhood and to maintain immunity throughout life. Cases of diphtheria have been reported in Viet Nam in recent years. The aim of this study was to evaluate the seroprevalence of IgG antibodies to diphtheria toxoid among healthy person population in Kon Tum, Viet Nam. Blood samples were obtained from 2225 healthy persons aged 2-98 years collected in 2019 and 2020. Samples were tested for diphtheria toxoid antibodies by commercial Anti-Diphtheria Toxoid IgG Enzyme-Linked Immunosorbent Assay (ELISA). An antibody level of