Immunogenicity persistence of hepatitis A vaccines Healive? and Havrix? among children:15 years follow-up and long-term prediction

Healive & REG; was the only Chinese WHO-prequalified inactivated vaccine for the hepatitis A virus, which has been widely used in national immunization programs in China. Long-term follow-up studies are needed to estimate the persistence of vaccine-induced antibody levels and the necessity for booster vaccines. During the trial, geometric mean concentrations (GMCs) and seroconversion rates (SRs) of anti-HAV antibodies were compared based on two different inactivated hepatitis A vaccines, Healive & REG; and Havrix & REG;. Four hundred children were randomly assigned to receive two doses of Healive & REG; or Havrix & REG; at 0 and 6 months. The current study assessed antibody persistence for both vaccines 15 years post-immunization. A mixed linear model was used to predict long-term antibody persistence. The GMCs were significantly higher for Healive & REG; compared to Havrix & REG; at 1, 6, 7, 66, 138 months (P < .001) and 186 months (P = .004 < .05) post-vaccination. Healive & REG; and Havrix & REG; reached a GMC of 164.8 mIU/ml and 105.7 mIU/ml post-15 years of vaccination, respectively. The seroconversion rates of both vaccines showed no statistically significant differences (97.9% for Healive & REG; and 94.7% for Havrix & REG;, P = .20). The prediction showed that Healive & REG; would provide protection for a minimum of 30 years following immunization, with a lower limit of the 95% confidence intervals for GMCs greater than 20mIU/mL. Compared to Havrix & REG;, the vaccine Healive & REG; showed a stronger protective effect and better persistence among children at 15 years post-full immunization. Prediction indicated at least 30 years of antibody persistence for Healive & REG; and at least 25 years for Havrix & REG;.