The last dose of Pentavalent is given at 18 months of age. The Pentavalent vaccine is usually a combination of diphtheria, pertussis, polio, tetanus, and Haemophilus influenzae. Four doses are usually required, usually three at 2, 3, and 4 months of age or 3, 4, and 5 months of age to complete the basic immunization. The last dose is given at 18 months of age to provide a booster immunization. Pentavalent vaccine can minimize the number of vaccinations, can reduce the pain caused by the number of doses, etc., many parents choose to vaccinate. Before vaccination, parents should understand the contraindications to vaccination, such as the child has fever, acute diseases and other contraindications, should be suspended vaccination.