FROM the seroepidemiological surveys presented at the recent London rubella conference1 and many of the others published, it is evident that the proportion of women of childbearing age without detectable antibodies varies between 8% to 20%. Furthermore, the development and persistence of seroimmunity as well as the decline of antibody levels with age and increasing time after infection are quite similar for most areas of the world.
This pattern was also found in our serologic survey. In this study, the hemagglutination-inhibiting (HI) antibody status and antibody level by age were determined in over 3,600 sera of the West German population including more than 1,800 samples from pregnant and nonpregnant women of childbearing age. The sera were obtained from various parts of West Germany during 1967 to 1969 and were stored at —20 C. For the HI test the sera were kaolin treated, and the lowest dilution tested was 1:8.