[Measles antibody followed after measles vaccination: comparison with gelatin beads agglutination (PA) antibody, hemagglutination inhibition (HI) antibody and IgG-avidity].

The immunity status of 37 cases has been tested at 6 weeks and 3.5 years after vaccination by using gelatin beads agglutination (PA), hemagglutination inhibition (HI) and avidity of specific IgG. The geometric mean titer (GMT) of HI antibody was 34.5 at 6 weeks and had fallen to 17.9 over 3.5 years. On the other hand, GMT of PA antibody was 36.5 at 6 weeks and had increased to 286.0 over 3.5 years. Also, the average of measles specific IgG avidity was 4.5% at 6 week and had increased to 45.4% over 3.5 years. The multiple regression analysis was performed in order to investigate the relationship of HI antibody and avidity to PA antibody. The significant involvement of the HI antibody and avidity to PA antibody (standardized partial regression coefficients; 0.612, 0.726) was recognized and the multiple correlation coefficient was 0.880 (p < 0.001). Hence it was strongly suggested that the increase of PA antibody with time could be dependent on that of IgG avidity.