There are many types of Class II vaccines. Polio vaccine and rotavirus vaccine are usually given at 2 months of age, while influenza vaccine is given at 6 months of age. There is no specific time for the vaccination of Class II vaccines, and the vaccination time varies for different vaccines. Class II vaccines mainly include polio vaccine, rotavirus vaccine, influenza vaccine, and chickenpox vaccine. Polio vaccine is given at 2 months of age, 3 months of age, 4 months of age and 18 months of age; Rotavirus vaccine can be given between the ages of 2 months and 5 years; influenza vaccine is given at 6 months of age or older; and varicella vaccine is given at 1 year of age or older. The time of vaccination varies for different vaccines. If you need to give your baby the second type of vaccine, you should take your child to the hospital for detailed consultation. Stay in the hospital for half an hour for observation after vaccination to avoid serious adverse reactions.