[Antibodies persistence after revaccination with three doses of hepatitis B vaccine in non-responsive adults: results from 8-year follow-up study].

Objective: To evaluate the persistence of HBsAg-specific antibodies eight years after revaccination with hepatitis B vaccine (HepB) among adults who were non-responsive to primary immunization. Methods: From August to September 2009, rural communities in Zhangqiu district of Ji'nan city were selected as the study site. The subject's inclusion criteria were 18 to 49 years old, local resident population, without HBV infection history and HepB vaccination history, and good health status. Antibodies against hepatitis B surface antigen (anti-HBs) were detected in adults following the standard primary vaccination. Those who were non-responders (anti-HBs titer <10 mIU/ml) were revaccinated with three doses of HepB and included in the study. Blood samples were collected from all of them at one month (T ₁ ), two years, four years, and eight years after revaccination. The three indexes of anti-HBs, hepatitis B surface antigen (HBsAg), together with antibody against hepatitis B core antigen (anti-HBc), were measured by chemiluminescence microparticle immunoassay (CMIA). Results: The proportion of subjects with anti-HBs titers ≥10 mIU/ml was 85.12% (549/645) at T ₁ , 60.60% (283/467) at two years, 55.90% (199/356) at four years and 55.09% (222/403) at eight years after revaccination. The first two years' annual decline rates, three to four years and five to eight years, were 15.62%, 3.96%, and 0.36%. The GMC of anti-HBs was 153.92 mIU/ml at T ₁ , 21.43 mIU/ml at two years, 15.02 mIU/ml at four years, and 13.68 mIU/ml at eight years. In the first two years, three to four years and five to eight years, the annual decline rate of GMC was 62.69%,16.28%, and 2.31%, respectively. Multivariable analysis showed that the titer of anti-HBs at T ₁ was independently associated with the persistence of anti-HBs at eight years after revaccination. Compared with anti-HBs titer <100 mIU/ml , those whose anti-HBs titers were 100-mIU/ml and ≥1 000 mIU/ml at T ₁ had a higher positive rate of anti-HBs ( OR =14.13, P <0.001; OR = 62.91, P <0.001) and a higher probability of anti-HBs titer ( β =1.88, P <0.001; β =3.24, P <0.001) at 8 years after revaccination. Nobody was found seroconversion of HBsAg, and the anti-HBc positive rate was 14.14% (57/403). Conclusions: Following revaccination with three doses of HepB in adults who were non-responsive to primary immunization, anti-HBs titers declined rapidly within the first four years. They then maintained a stable level after the fifth year. More than half still kept anti-HBs protective titer at eight years after revaccination. The immunity persistence was associated with anti-HBs titer at one month after revaccination.