At what age does the oral polio vaccine start and is it free?

Polio vaccine is polio vaccine, at present, China’s polio vaccine is injected from the first dose of inactivated polio vaccine when the baby is two months old, and then injected a dose of inactivated polio vaccine at one-month intervals, and oral live attenuated polio vaccine at 4 months old, and then orally at 4 years old again. Oral polio vaccine is a national class I vaccine and is free of charge. Oral polio vaccine is usually given as one dose at four months of age and a booster dose at four years of age. Oral polio vaccine can make babies develop antibodies, which can effectively avoid and prevent the occurrence of polio in babies. There are Class I and Class II vaccines. Class I vaccines belong to the national immunization and are free of charge, while polio vaccine belongs to Class I vaccines. If there is any adverse reaction after polio vaccination, you need to go to the hospital for treatment.