At this stage, the third dose of vaccine is generally referred to as the booster shot of the New Crown Vaccine, which is not recommended for children aged 12-17 years old at this time, and the booster shot is only available for children aged 18 years old and above. After vaccination, antibodies will be produced in the body, and the titer concentration of the antibodies produced marks the ability of the vaccine to resist the virus. Generally speaking, the higher the titer of the neutralizing antibody, the better the immunogenicity of the vaccine. According to the current vaccination regulations, children between the ages of 12 and 17 only need to receive two doses of the vaccine, and the third booster shot is not available at this time. However, after the first vaccination, the neutralizing antibody titer in the blood is very low, and even though the titer of the neutralizing antibody in the body is much higher after the second vaccination, it will gradually decrease over time. Prevention is important in the new coronavirus pneumonia outbreak, and it is recommended that adolescents and young adults of the appropriate age be vaccinated in a timely manner to reduce the risk of infection. Tip: The terms “new coronavirus pneumonia” and “new coronavirus pneumonia” mentioned in this article were renamed to “new coronavirus infection” on December 26, 2022, as announced by the National Health Commission.