There are currently two types of hepatitis A vaccines for babies: live attenuated vaccine (self-pay) and inactivated vaccine (free). Inactivated vaccines are vaccines made by inactivating pathogenic microorganisms (including bacteria, viruses and rickettsiae, etc.) and their metabolites by physical or chemical means, losing their virulence but still retaining their immunogenicity, such as pertussis vaccine and influenza vaccine. These vaccines require large doses and many injections because the pathogenic microorganisms have been killed and cannot grow and multiply after entering the human body. Generally, the immunity produced after one injection is not high, and 2-3 injections or booster injections are needed to produce a more satisfactory immunity. However, inactivated vaccines have good stability and are easy to preserve. Live attenuated vaccines are made by taking pathogenic microorganisms (bacteria and viruses) and making them lose their pathogenicity under artificial conditions, but still retaining their ability to reproduce and immunogenicity. Live attenuated vaccines are administered to humans to produce a subclinical infection, similar to a mild artificial natural infection process, which causes an immune response similar to that of the disease, but without the onset of disease, but with immunity against the species. It has a long duration of action in the body and often requires only one vaccination to produce a solid immunity, such as polio vaccine and measles vaccine. Live lyophilized attenuated hepatitis A vaccine: The live attenuated hepatitis A vaccine is made by inoculating the genetically stable and safe for human H2 attenuated strain in human diploid cell culture, then extracting, purifying and concentrating it with an advanced process, and finally dissolving it in a salt-balanced solution containing various amino acids. Unlike the general live virus vaccine, it is a purified live vaccine. The immune mechanism of the domestic HA live attenuated vaccine may be a combination of live virus proliferation and dead antigen stimulation, and therefore, the live vaccine booster immunity is excellent. After 1 dose of booster immunization with the regulated live attenuated HA vaccine, the antibody positive conversion rate can reach 100% and the antibody GMT can reach 3000 mIU/ml, which is several hundred times higher than that of receiving 1 dose of live vaccine, and the live vaccine re-vaccination may be beneficial to improve the vaccine protection and extend the protection years.An important issue with the live attenuated HA vaccine is that the field use needs to provide high titers, otherwise it is impossible to produce a good immune response. Both live attenuated hepatitis A vaccine and inactivated hepatitis A vaccine fall within the scope of the national immunization plan vaccines, and the specific types of inclusion may be determined by each province. Whether self-funded or free, they are both qualified vaccines issued by the state. The difference between the two: The virus in live attenuated vaccine has reduced activity, but is still active and can proliferate in the baby’s body, interacting with the body’s cells for a long time and inducing a stronger immunity. For babies with immune deficiencies, vaccines should be chosen with extra care and “inactivated vaccines” should be used instead of “live attenuated vaccines”.