BACKGROUNDTo determine the long-term efficacy and persistence of Chinese infants after receiving only active plasma-derived hepatitis B vaccine, and to evaluate if providing booster vaccination after basic hepatitis B immunization is necessary.

METHODSInfants who were born in 1986-1988 in four demonstrative hepatitis B immunization trial areas of Hunan, Guangxi, Hebei and Shanghai after receiving only active plasma-derived hepatitis B vaccination, had been randomly followed up for 15 years. HBsAg,anti-HBs and anti-HBc in 21 680 person-times were tested using commercial SPRIA kits.

RESULTSPrevalence of HBV carriers was less than 1.66% among all children vaccinated with only active plasma-derived hepatitis B vaccine in 4 clinical trial areas. Prevalence of HBsAg did not increase with years after vaccination,90%(95% Cl:83.1%-97.2%) effectiveness of hepatitis B vaccine persisted for 15 years in preventing chronic HBV infection. Carriage, HBV infection and efficacy were not different among all age groups (P>0.05). Seroprotection rate (anti-HBs?10 mIU/ml) and quantity of anti-HBs were significantly decreased with years after vaccination. Seroprotection rates of anti-HBs were 40%-50% and 30%-42% during the 9th-10th year and the 13th-14th ear of vaccination, respectively. Titer of anti-HBs declined?by 90% after 14 years.

CONCLUSIONSThese results showed that long-term efficacy of only active plasma-derived hepatitis B vaccination, which was not affected by decline in seroprotection rate and titer of anti-HBs. For children and adults whose immune status is normal, booster doses of vaccine are not recommended.