If your child is vaccinated there should be no problem your child will not get the disease. It is no different than if you send your child to school with sun screen and his friend doesn’t have sun screen. Your child wouldn’t get sun burnt but the other one will.
There are two issues here:
1. Some people, for various reasons, cannot be vaccinated.
2. Vaccinations are not necessarily 100% effective. Sometimes you can get a vaccine and still come down with the disease if you come in contact with an infected person.
In both of these cases, “herd immunity” protects them from coming down with the disease in question. By having a general population that is vaccinated, the chances of them coming down with the disease is much lower.
The Wolf