Enhanced immunization and sequential immunization refer to homologous enhanced immunization and sequential enhanced immunization. Both homologous enhanced immunization and sequential enhanced immunization are able to further improve the immunization effect, so it is usually not possible to judge which of the two is better. 1. Homologous booster immunization: booster immunization uses the same technical route of vaccine as basic immunization for vaccination, which means that after the completion of vaccination, supplemental vaccination is carried out according to the situation of antibody fading. 2. Sequential booster vaccination: booster vaccination is carried out with vaccines of different technical routes from the basic immunization. For example, after the completion of two inactivated New Crown vaccines, the follow-up booster vaccination is completed with other New Crown vaccines that are not inactivated. Before the vaccination must pay attention to not empty stomach, do not take a shower on the first day after the vaccine, after 24 hours can take a normal shower, at the same time pay attention to there is no obvious redness, pain and other symptoms, if there is any discomfort in a timely manner to seek medical attention.