There is no booster for the time being after the three doses of Zhifei Xinguan vaccine. Currently, booster vaccinations are implemented with inactivated vaccines from Sinopharm Zhongsheng Beijing Biological Institute, Beijing Kexing Zhongwei Biological Company, and adenovirus vector vaccine from Tianjin Kangxinuo Company. After the first vaccination, it will leave a memory for the body’s immune system, and the subsequent vaccinations are to train the immune system to recall the immunity. If you want the vaccine to be effective, it is not better to give it as many times as possible. Sometimes, it not only fails to improve the body’s immunity, but also may have some side effects on the human body. The Jiffy Crown vaccine is able to achieve the desired goal after three doses, so there is no need for a booster at this time.