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.