Fact 6: Scientific evidence shows that giving several vaccines at the same time has no adverse effect on a child’s immune system. Children are exposed to several hundred foreign substances that trigger an immune response every day. The simple act of eating food introduces new antigens into the body, and numerous bacteria live in the mouth and nose. A child is exposed to far more antigens from a common cold or sore throat than they are from vaccines. Key advantages of having several vaccines at once is fewer clinic visits, which saves time and money, and children are more likely to complete the recommended vaccinations on schedule. Also, when it is possible to have a combined vaccination, e.g. for measles, mumps and rubella, that means fewer injections.