The difference between recombinant protein vaccine and inactivated vaccine is reflected in their production process as well as their respective advantages and disadvantages, and recombinant protein vaccine, as a post-emerging vaccine type, still has more room for development. Because of the different immunity, the number of vaccinations differs between the two vaccines, and the specific vaccination time and number should be judged according to the type of vaccine. The vaccine is produced by expression and purification. This vaccine is now commonly used in the new crown recombinant vaccine and is usually given in three doses, with the first and second doses given 4-8 weeks apart and the second and third doses given 4 weeks apart, with the three doses given within 6 months. The biggest advantage compared with traditional vaccine is that it can use genetic engineering technology to differentiate pathogens, which can preserve some genes that play an immune and protective role for the body and remove the invalid genes, and the safety and effectiveness are also guaranteed. 2. Inactivated vaccines: Vaccines made by physically or chemically killing pathogenic microorganisms so that they lose their ability to reproduce but retain their immunogenicity. This vaccine is now commonly used in the new crown inactivated vaccine, and two doses are usually administered clinically, with a recommended interval of 3-8 weeks between the two doses. The advantages are good safety, strong and long-lasting immunity, little interference with the immune effect by maternal antibodies, and no interference with antibiotics. The disadvantages are that the dose of vaccination is large, the route of vaccination is small, and the duration of the induced immune response is short, requiring multiple vaccinations, and the vaccine is difficult to absorb and nodules tend to form at the injection site. Since this vaccine usually takes more than 10 days to produce immunity after injection, it is not suitable for emergency vaccination.