Currently in the domestic market, the vaccines used to prevent hepatitis A can be divided into two types: domestic live attenuated hepatitis A vaccine and imported purified inactivated hepatitis A vaccine. So, what is the difference between the two? The domestic live attenuated hepatitis A vaccine has good immunity and is relatively easy to administer, requiring only one vaccination, and is also inexpensive. The imported hepatitis A vaccine, on the other hand, is a dead vaccine that requires two doses, with a second dose 6 months apart after the first dose, and can be relatively expensive. Although there are differences between the domestic and imported hepatitis A vaccines, for those who need to receive the hepatitis A vaccine, choosing either one will protect them against the hepatitis A virus. About 8 weeks after receiving the hepatitis A vaccine, the body can produce very high levels of antibodies and obtain good immunity. The antibody positivity rate can be 98%-100%, with good immune persistence, and immunity generally lasts for 5-10 years. What is the specific difference between live attenuated vaccines and inactivated vaccines? Live attenuated vaccine is a live or live attenuated vaccine made by artificially directed mutation or by screening live microorganisms from nature with reduced virulence or basically non-virulent. In layman’s terms, the vaccine is live, but is generally made from “non-toxic or very low virulence, but highly immunogenic strains of viruses or mycoplasma” that have been cultured and propagated. It can produce protective antibodies and enhance the activation, recognition and phagocytosis of cellular immunity. The amount of live vaccine is smaller and the duration of immunity is longer. The immunization effect of live vaccines is better than that of dead vaccines. What is an inactivated vaccine? I.e. bacteria, viruses, rickettsiae, spirochetes, etc. with good immunogenicity are selected, artificially cultured, and then killed by physical or chemical methods. This vaccine loses the ability to reproduce, but retains immunogenicity. After entering the human body, the dead vaccine cannot grow and reproduce, and has a short stimulation time for the organism, and several repeated vaccinations are required to obtain lasting immunity. This is why inactivated hepatitis A vaccine, needs to be given twice. In layman’s terms, an inactivated vaccine is a killed virus that is introduced into the body so that it does not cause disease but also allows the body to produce antibodies to defend itself against viral invasion.