ABSTRACT
<p><b>OBJECTIVE</b>To introduce exponent curve model methods in the study of the hepatitis B vaccine antibody level.</p><p><b>METHODS</b>After the China made vaccine of hepatitis B DNA recombinant yeast derived vaccine (YDV) had been carried out for 5 years, data on the anti-HBsAg's titer were used to construct an exponent curve model. When the vaccination program had been carried out for 8 years, the predicating results of the model were further tested by observed number.</p><p><b>RESULTS</b>The exponent curve model was Y = 165.67 exp (-0.019X) and the R(2) was 0.98. After 8 years, the practical observed number became 35 mIU/ml, and the predicating result of the model was 27 mIU/ml, 8 mIU/ml lower than the observed number. When the vaccine had been carried out for 12 years, the predicating results of the model became 10.74 mIU/ml, still higher than 10 mIU/ml but was still in the effective range.</p><p><b>CONCLUSION</b>An exponent curve model could be constructed, as long as the data of the antibody's titer was in accordance with the tendency of exponent curve. The model could be used to predict the persistence lever of vaccine antibody under certain conditions. The results showed that after 8 years, the predicting results of the model were reliably lower than the observed number.</p>