Vaccine mixing refers to the use of different manufacturers or different types of vaccines in the same immunization program. In some cases, it is possible, for example, the vaccination of the new crown vaccine uses a different type of vaccine, the details vary depending on the type of vaccine, and it is recommended to consult with the doctor at the vaccination site before vaccination. Mixed vaccination means that the two doses of vaccine received belong to different manufacturers or are of different types. This is usually seen in cases where the two doses of vaccine are administered in different places or when there is a shortage of vaccine. Preliminary studies have shown that the safety and efficacy of vaccines are not significantly affected by mixing vaccines of the same type from different manufacturers. For example, in the booster vaccination of Xin Guan vaccine, different types of vaccines can be used for the basic immunization program and booster vaccine, and one dose of adenovirus vector vaccine or one dose of recombinant protein vaccine can be selected after completing the basic immunization of 2 doses of inactivated vaccine for 6 months. However, it is important not to mix two different vaccines in one syringe, as this may lead to severe allergic reactions and toxic reactions, which may be life-threatening in severe cases. If more than one vaccine is needed at the same time, the vaccinations are usually given at least 2 weeks apart. After vaccination, the patient should be kept under observation for 30 minutes and should inform the doctor promptly if any discomfort such as panic or chest tightness occurs.