Usually children need the same vaccines as adults when travelling abroad.
The risk of getting infected is not smaller for children than adults when going abroad. In the case of some infections (for example hepatitis A, typhoid, tuberculosis, meningitis and rabies) the risk can be bigger for children than adults, especially for children who are stationed abroad for a longer period of time with their parents. When stationed abroad they reside locally with greater risk for transference of disease through water, like hepatitis and typhoid. They will also be near local children with which follows an enhanced risk for infection with meningitis, diphtheria and tuberculosis.
Apart from the infections especially related to travel, children have the risk of being massively exposed to the common children’s diseases. German measles and mumps are not significant in this context since they only cause a mild illness with children, measles, however, is a serious risk to a child who has not been immunized. The vaccines you are supposed to have, as a child, should be brought in order before leaving the country.