[Dynamics of diphtheria morbidity and population immunity]

Observations on the stratum immune to diphtheria among the population, carried out over a period of many years and involving more than 37,000 people, have shown its gradual decrease in all adult age groups. In recent years the number of adults susceptible to diphtheria exceeded the number of susceptible children by 10.6%, and in some age groups by 18.5-21.8%, which makes for the total increase of diphtheria morbidity in recent years owing to its rise among adults. Regular revaccination of the adult population against diphtheria, made simultaneously with that against tetanus, is recommended.