In most cases, six-month-old infants can be vaccinated at the same time as the hepatitis B vaccine because some children’s vaccinations are delayed, for example, the diphtheria vaccination starts three months after birth and is given once a month apart. If an infant has a cold and the last dose of diphtheria is delayed until six months of age, the vaccination can be given at the same time as the hepatitis B vaccine, but only at different sites. The safety of both vaccines is relatively good, and the simultaneous vaccination of children will rarely cause adverse reactions such as high fever and vomiting.