The third polio shot is necessary and belongs to the vaccines in the national immunization program. The third polio injection refers to the third injection of the live attenuated polio vaccine. The vaccine is administered to infants at 2, 3, and 4 months of age, with an interval of more than 4 weeks each time, and a booster injection is required at 4 years of age. Although polio has been basically eradicated from our country, the disease mainly affects children under five years of age, and so it is recommended that the third injection of the polio vaccine be administered. Polio vaccination can effectively prevent the occurrence of polio. Polio may cause muscle paralysis, atrophy and affect limb function. Therefore, the third shot of the live attenuated polio vaccine, is necessary to do the whole vaccination to avoid infection.