[Seroimmunity against rubella 5 years after immunisation with Cendehill vaccine (author's transl)]

The HI-antibodies against rubella of 383 schoolgirls, vaccinated with the Cendehill vaccine between 1969 and 1973 were investigated 8 weeks and 1,9 to 5 years, respectively, after the immunisation. The geometric mean titer of the sera investigated was 1 : 81 in the second sera. 69% of the girls, immunized at the age of 15 to 17 years in 1973 had identical serotiters in the 1st and 2nd serum samples, whilst those vaccinated between 1969 and 1971 had only in 54% constant titers. The geometric mean titer varied between 1 : 91 and 1 : 73. 33% of those vaccinated between 1969 and 1971 and 24% of the vaccinees from 1973 had a fourfold increase in the serotiter in the second postvaccinal serum. A decrease in titer could be demonstrated between 7% to 13% in different periods. Only 1% of the sera investigated became seronegative. The fourfold increases in titers are probably due to inapparent clinical rubella infections, leading to a not undesirable booster of immunity.