| immunity against diphtheria in adults in poland. | the diphtheria immunity status was determined with the passive haemagglutination technique in 503 sera of 10-90-year-old persons from warsaw and olsztyn provinces. donors of sera were students, teachers, pregnant women, employees of industry and medical service. the immunity was highest (90% of titers 0.1 iu/ml or higher) in persons below 20 years of age and in persons above 60 years of age (55%). between these two groups, gaps in immunity exist, the proportion of those immune varying from 36-50 ... | 1989 | 2514113 |