Vaccines in circulation differ in the number of doses required depending on how they are made and the diseases they target, so their effectiveness varies. For one-shot vaccines, one shot is sufficient to achieve the desired clinical effect, such as pneumonia vaccine and tetanus vaccine. For vaccines that require multiple doses, such as chickenpox vaccine and hepatitis B vaccine, only one dose will not achieve the desired clinical effect. For vaccines that require multiple doses, one dose may also have some effect, but the effect is weak and short-lived. If you want to achieve a more desirable clinical result, you need to follow the prescribed number of doses of the vaccine. During the first vaccination, the vaccine component enters the body and stimulates the immune system to produce antibodies, which have a weak effect for a short period of time. The initial antibodies produced have a weak effect, but the duration of action is shorter. Vaccines that have been approved for marketing by the state have been tested for their safety and clinical effectiveness, and should be administered according to the prescribed time and requirements, and generally achieve better clinical expectations.