Booster shots are generally referred to as New Crown booster shots. There is no strict time frame as to how late the third booster shot of New Crown can be completed, but it is good to get vaccinated early as required. The purpose of the third booster is to increase the antibody level of the vaccinee significantly and maintain it at a high level, and to enhance the protective effect of the vaccine with good cross-neutralization against the Delta and other mutated strains. There is no strict time limit for the completion of the third booster vaccination. If you forget to take the vaccination at the latest, it does not matter how long it takes, you just need to take the additional vaccination as early as possible in accordance with the time limit in order to have a good effect of strengthening the immunization. The third booster vaccination needs to have completed two doses of inactivated vaccination and the second dose is 180 days away from now, and people over 18 years old should be vaccinated in time if they meet the above conditions.