[Variations of hepatitis B virus infection epidemic pattern after long-term HBV vaccine immunization].

OBJECTIVE: To study the epidemic pattern and trend of HBV infection in the area where the people had been immunized by HBV vaccine for 20 years. METHODS: The whole sampling method was applied in combination with cross-sectional investigation. Blood samples were taken from every member of families. Markers of HBV infection were determined by using solid-phase radioimmunoassay (SPRIA). RESULTS: (1) The average HBsAg positive rate was 7.5%. The positive rate of markers for HBV infection of 0-19 years old subjects were lower than those of > or = 20 years old subjects. (2) The positive rate of HBsAg of 0-19 years old subjects in 1985 was higher than that in 2005. The anti-HBs positive rate in 1985 stemmed to be higher with age. It was 12.4% in 1- age group to 53.8% in >60 years age group. While the result of 2005 showed that the anti-HBs positive rate of 0-19 years old subjects dropped with age. The anti-HBc positive rate in 1985 also tended to be higher with age. But the result of 2005 showed that the rate of 0-19 years old subjects was just 1.4% to 16.8%. CONCLUSION: The epidemic patterns of HBV infection have had significant variations in the target population. HBV vaccine immunization has obtained excellent efficacy.