Immunogenicity and Safety of Hepatitis A Among People Aged 18-50 Years Old

Inclusion Criteria: * Adults aged 18-50; * Adults can understand and sign the informed consent form voluntarily; * Adults can provide valid and legal identity certificate. Exclusion Criteria: * A history of hepatitis A infection; * Previously vaccinated with inactivated hepatitis A vaccine, live attenuated hepatitis A vaccine, or hepatitis A and B combined vaccine; * Allergic constitution or have severe allergic reaction to vaccines in the past (such as acute allergic reaction, angioedema, dyspnea, etc.); * Pregnant women and lactating women; * People suffering from uncontrolled epilepsy and other serious neurological diseases (such as transverse myelitis, Guillain-Barré syndrome, demyelinating diseases, etc.); * Patients with fever during vaccination, or acute exacerbation of chronic diseases, or patients with uncontrolled severe chronic diseases, or suffering from acute diseases; * Received other research drugs within 30 days before vaccination with the experimental vaccine; * Have received a live attenuated vaccine within 14 days before vaccination with the experimental vaccine; * Have received subunit or inactivated vaccine within 7 days before vaccination with experimental vaccine; * Other conditions that are not suitable for vaccination judged by the researcher.