From the available information, the safety of sequential booster immunization is good with fewer side effects, although everyone’s health condition is different, and if the adverse effects of certain vaccines are more pronounced for an individual, he or she may choose other vaccines. Sequential vaccination is just a vaccination strategy for booster shots, which means choosing a vaccine for booster immunization that is different from the previous vaccine’s technical route, e.g., the previous New Crown vaccine was an inactivated vaccine, while the booster shot was chosen to be a non-inactivated vaccine. A single vaccine is usually sufficient for routine, easily preventable viruses or diseases, but for certain viruses that are highly variable and difficult to treat, sequential immunization is required. Everyone’s constitution is different, so if you have a more pronounced adverse reaction to a certain vaccine, you can choose a different one to avoid side effects. After vaccination, you need to stay for half an hour, if there are adverse reactions such as rash and fever, they usually subside in about 3 days, if they persist, it is recommended to consult a doctor in time.