There is really nothing in any religion against vaccinations, as all the religions were created before the concept of vaccination was introduced. But then, most people who practice a religion do not actually know much about what their religion says and if some foolish priest, minister, preacher or whatever decides that the religion requires this or bans that, it is rare that the members of the congregation will question him. That is how barbaric nonsense like female circumcision became part of Islam. Male circumcision may make STD's more difficult to contract and is not so disfiguring. Of course, the original purpose was to prevent a major cause of military defeat: soldiers who saw that the other side was winning and changed their uniforms for one from a dead enemy. If the soldier was circumcised, he could not deny that he was Jewish or Muslim and it was therefore an advantage to members of those religions.
In ancient times, wars were mostly fought for plunder and territory and no one wanted to be on the losing side, as it usually meant that you would be a slave.
I agree that children hate getting shots, I still dislike blood tests and shots myself. But since the benefits outweigh the brief discomfort, I never complain.
It is the responsibility of the parent to explain how shots work to children.
