Assessment on booster immunization of inactivated hepatitis A vaccine in healthy infants

[Objective]To assess the effectiveness and safety of the booster immunization with inactivated hepatitis A vaccine,provide a complement for hepatitis A immunization strategy.[Methods]100 24-38 months old children who have completed the attenuated hepatitis A vaccination 6 months ago received the booster immunization with one dose of inactivated hepatitis A vaccine.After one month,the levels of anti-HAs before and after immunization were detected,in order to evaluate the geometric mean concentration(GMC) and the positive rate.The clinical symptoms were observed for 3 three days to assess its safety.[Results]One month after immunization,the positive rate of hepatitis A antibody increased from 95.2% before immunization to 100%,the GMC increased from 124.4 mIU/ml to 7 269.3 mIU / ml,by 55.7 times.There were 12 cases of adverse reactions with the incidence rate of 5.7%,and all were fever.Severe adverse reaction was not found.[Conclusion]The booster immunization with inactivated hepatitis A vaccine has good immunogenicity and safety.It is proposed to increase the booster immunization with one dose to enhance long-term antibody protection.