RESUMEN
OBJECTIVE: To observe the long-term effect of plasma-derived HBV vaccine. METHODS: The effect of a plasma-derived HBV vaccine which was given to children born in 1986 in Huangpu district in Shanghai were followed up once every two years and testing for HBsAg, anti-HBs and anti-HBc was carried out. Compared to background results from cross-sectional survey of hepatitis B virus in 1984 and 1985 (as internal control) as well as finding of survey targeted in non-plasma-derived HBV vaccine of children born in the same time in the nearby area from results investigated in 1991 (as external control), positive rate was calculated to assess the effect of protection. RESULTS: The population immunized was followed up for 23 years and 5993 blood samples were collected. During the period of follow-up, the positive rate of anti-HBs decreased from 89.01% to 18.77% and the average level was 40.39%. The average positive rate of anti-HBc was 1.87%. The annual positive rate fluctuated around the average level. HBsAg positive rate remained less than 1.00% (0.46% - 0.98%), with an average of 0.62% (37/5993). Ranges of positive efficacy were from 81.37% to 95.78% against background control and 72.76% against external control. CONCLUSION: The plasma-derived HBV vaccine showed a good long-term protective effect and there was no need for boosting the immunization 23 years later.
