If the third vaccine is the third booster of the new crown vaccine, you need to be 18 years old; there is no age limit for other vaccines such as Hepatitis B vaccine and cervical cancer screening. If the third booster shot of the new crown vaccine is given, there is a clear age restriction for the people to be vaccinated, they must be 18 years old or older, otherwise they cannot receive the third shot. However, if the 3rd shot refers to Hepatitis B vaccine, you don’t have to be 18 years old, because there is no clear age restriction for the third shot of Hepatitis B vaccine, and people under 18 years old can be vaccinated, and the third shot of Hepatitis B vaccine needs to be completed within 6 months so that the immunization effect is a little better. Before taking the vaccine, you need to have a certain understanding of the type of vaccine and the vaccination process, and if you are not sure whether you can take the vaccine, you can consult a professional vaccinator to avoid any adverse effects on your health.