There is no problem with the third vaccination being more than 6 months apart from the second, the vaccine is still valid. If you are not sure whether you can receive the vaccine, it is advisable to consult the doctor at the vaccination site. At present, the main types of vaccines that require three doses are inactivated vaccines and recombinant subunit vaccines. The inactivated vaccine program consists of two doses, with an interval of three weeks (or more) between the first and second doses, and a booster vaccination six months after the completion of the second dose. If the interval is more than six months, a booster immunization can still be given and the vaccine is still effective. For recombinant subunit vaccine, 3 doses are required. The recommended interval between two adjacent doses is 4 weeks (or more). The second dose should be completed as close as possible to 8 weeks after the first dose, and the third dose should be completed as close as possible to 6 months after the first dose. If the third dose is not given within the prescribed time, there is no need to restart the immunization program. Early catch-up vaccination is sufficient and will hardly affect the protective effect of the vaccine. For other vaccines that require three doses, such as Hepatitis B vaccine and HPV vaccine, the third dose can still be given beyond 6 months without restarting the immunization program, and the effectiveness of the vaccine will not be reduced.