AIM To understand the anti-HBs persistenceand the long-term preventive efficacy in ruralnewborns after vaccination with plasma-derivedhepatitis B vaccine.METHODS In the time of expanded program onimmunization(EPI),the newborns werevaccinated with 10μg×3 doses of hepatitis Bvaccine and 762 newborns who were HBsAgnegative after primary immunization wereselected for cohort observation from 1986 to1998.Their serum samples were detectedqualitatively and quantitatively for hepatitis Binfecting markers,including HBsAg,anti-HBsand anti-HBc by SPRIA Kits.The annual HBsAgpositive conversion rate was counted by life-table method.RESULTS①The anti-HBs positive rate was94.44% for the babies born to HBsAg negativemothers and 84.21% for those born to HBsAgpositive mothers in the 1st year afterimmunization,and dropped to 51.31% and52.50% in the 12th year respectively.GMT valuewas dropped from 31.62 to 3.13 and 23.99 to 3.65in the 2nd to the 12th year respectively.Therewas a marked drop in GMT at the 3rd to the 5thyear,and in anti-HBs positive rate at the 9th tothe 10th year.②In the period of 12 yearsobservation,the person-year HBsAg positive conversion rates were 0.12%(5/4150.0)innewborns born to HBsAg negative mothers and0.20%(1/508.0)in those born to HBsAgpositive mothers,and none of the HBsAgpositive converted children became HBsAgchronic carriers.Compared with the baselinebefore immunization,the protective rates were97.19% and 95.32% respectively.CONCLUSION The protective efficacy ofplasma-derived hepatitis B vaccine persisted atleast 12 years,and a booster dose seems notnecessary within at least 12 years after theprimary three-doses immunization to newbornsborn to HBsAg negative mothers. AIM To understand the anti-HBs persistence and the long-term preventive efficacy in rural newborns after vaccination with plasma-derived hepatitis B vaccine. METHODS In the time of expanded program on immunization (EPI), the newborns werevaccinated with 10 μg × 3 doses of hepatitis Bvaccine and 762 newborns who were HBsAgnegative after primary immunization were selected for cohort observation from 1986 to 1998. Their serum samples were detected qualitatively and quantitatively for hepatitis Binfecting markers, including HBsAg, anti-HBs and anti-HBc by SPRIA Kits. The annual HBsAgpositive conversion rate was counted by life- table method. RESULTS ① The anti-HBs positive rate was 94.44% for the babies born to HBsAg negative mothers and 84.21% for those born to HBsAgpositive mothers in the 1st year after immunization, and dropped to 51.31% and52.50% in the 12th year respectively. GMT value is dropped from 31.62 to 3.13 and 23.99 to 3.65 in the 2nd to the 12th year respectively.Therewas a marked drop in GMT at th e 3rd to the 5thyear, and in anti-HBs positive rate at the 9th tothe 10th year. ②In the period of 12 yearsobservation, the person-year HBsAg positive conversion rates were 0.12% (5 / 4150.0) in newborns born to HBsAg negative mothers and0 .20% (1/508.0) in those born to HBsAgpositive mothers, and none of the HBsAgpositive converted children became HBsAg carriers. Compared with the baselinebefore immunization, the protective rates were97.19% and 95.32% respectively. CONCLUSION The protective efficacy ofplasma- derived hepatitis B vaccine persisted atleast 12 years, and a booster dose seems not necessaryary at least 12 years after the prrimary three-doses immunization to newbornsborn to HBsAg negative mothers.