This is a randomized, double-blind clinical trial of two inactivated hepatitis A vaccines in healthy children, immunogenicity and interchangeability of the two inactivated hepatitis A vaccines were evaluated.

This was a monocenter, comparative trial in which healthy children were randomized to receive two doses of hepatitis A vaccine 6 months apart. The trial was conducted in accordance with the Edinburgh version of the Declaration of Helsinki. The study was approved by the Ethics Committee. Parents or legal guardians of all participants gave written informed consent prior to study entry. Eligible subjects were between 18m and 6 years of age, When enrolled, children were randomized to four equal groups with different intervention. Immunogenicity and interchangeability of two inactivated hepatitis A vaccines were evaluated.

Inclusion Criteria:

• Healthy children aged between 1.5 and 5 years, with no history of hepatitis A virus infection or hepatitis A vaccine vaccination
• Provided birth certification or vaccination card
• Parent(s) or legal guardian(s) are able to understand and sign the informed consent

Exclusion Criteria:

• Axillary temperature > 37.0 centigrade at the time of dosing
• Subject that has a medical history of any of the following: allergic history, or allergic to any ingredient of vaccine
• Serious adverse reactions to vaccines such as anaphylaxis, hives, respiratory difficulty, angioedema, or abdominal pain
• Autoimmune disease or immunodeficiency
• Congenital malformation, developmental disorders or serious chronic diseases (such as Down's syndrome, diabetes, sickle cell anemia or neurological disorders)
• Bleeding disorder diagnosed by a doctor (e.g. factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or significant bruising or bleeding difficulties with IM injections or blood draws
• History or family history of convulsions, epilepsy, brain disease and psychiatric
• History of any blood products within 3 months
• Administration of any other investigational research agents within 30 days
• Administration of any live attenuated vaccine within 30 days
• Administration of subunit or inactivated vaccines within 14 days
• Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer's ability to give informed consent