Nowadays, the main types of neo-coronavirus vaccines are inactivated vaccines, adenovirus vector vaccines and recombinant subunit vaccines, among which recombinant subunit neo-coronavirus vaccine (CHO cells), which is the vaccine that requires three doses, has been proven by clinical data to improve immunity as well. According to the recommendations in the “Technical Guidelines for Vaccination against Neocoronavirus (First Edition)” issued by the state, three doses of recombinant subunit neocoronavirus vaccine (CHO cells) are required, with an interval of ≥4 weeks between adjacent doses, and three doses of vaccine need to be completed within 6 months for optimal immunity. There is also a situation where antibodies decline over time after vaccination and a booster dose, the third dose of the inactivated New Crown vaccine, can be administered after 6 months. Research data also show that the third dose of vaccination can suggest the protective effect of the immunogen, and China has started the third dose of booster vaccination of the relevant live vaccine, which may start as long as the following parts of the population are completed: 1. people at high risk of importation: customs, border control, aviation, isolation points, designated medical institutions and other staff, who can carry out the booster vaccination; 2. people with relatively low immune function: for example, 60 People over 60 years old, who are more prone to the risk of serious illness and death after being infected with the virus, can also receive the third vaccination in order to reduce the risk of infection; 3. People who need to go to high-risk areas or countries abroad: With the gradual restoration of social order, some people need to study or work abroad and may go to countries with more serious epidemics, and it is also recommended to receive the third vaccination.