OBJECTIVETo study the safety and immunogenicity of the Bilive combined hepatitis A and B vaccine produced by Sinovac Biotech Co., Ltd.

METHODSSamples were selected from first year students of a senior high school (adults group) and first to fifth grade 1-5 students of 3 primary schools (children group). Those who were susceptible to both hepatitis A virus (HAV) and hepatitis B virus (HBV), HAV only or HBV only were assigned to group AB, A and B respectively and were vaccinated with three doses (0, 1 and 6 month schedule) of Bilive combined hepatitis A and B vaccine, inactivated hepatitis A vaccine and recombined hepatitis B vaccine respectively. The dosage for adult group was 500 U hepatitis A antigen and/or 10 micro g hepatitis B surface antigen and the dosage for children group was half the dosage of adult group. The potential adverse effects were observed within 72 hours after vaccination. Serum samples were collected for testing anti-HAV and anti-HBs at month 2 and 7 after the initial dose.

RESULTSThe rates of local adverse effects were 0.58% and 2.56% in children AB group and adults AB group and the general adverse effects rates were 9.88% and 5.45% respectively. Both local and general adverse effect rates were not significantly different to the control group. The sero-conversion rate of anti-HAV in children and adults AB group reached 100%, one month after 3 doses. The geometric mean titer (GMTs) reached 33,910 mIU/ml and 23,435 mIU/ml respectively, significant higher than that in control group (group A). The sero-conversion rates of anti-HBs were 97.30% and 96.63%, and GMTs were 103 mIU/ml and 102 mIU/ml in children and adults AB group respectively. No significant difference on sero-conversion and GMT was observed when compared with control group.

CONCLUSIONThe Bilive combined hepatitis A and B vaccine had good safety profile, and the immunogenicity both on anti-HAV and anti-HBs was similar to that of separated components.