Diphtheria - assessment of immune status in newly enlisted professional soldiers in the Czech Republic.

Diphtheria is a serious bacterial infectious disease whose occurrence has been reported again in Europe in recent years. The aim of this study was to assess the level of antibody immunity against diphtheria among newly enlisted professional soldiers in the Czech Armed Forces. Between 2017 and 2023, IgG antibody levels against diphtheria toxin were measured in 1,116 individuals using the ELISA method. Only 1.6% of individuals demonstrated long-term protection, and sufficient seroprotection was observed in 25.3% of those tested. A total of 73.1% of adults had uncertain or insufficient antibody levels. A decline in antibody levels was evident with increasing age. The results point to a significant waning of post-vaccination immunity in the adult population and support the need for regular diphtheria booster doses, particularly among high-risk occupational groups.