No vaccinations yet, at age six???
That means you must ensure your poor son always stays within areas where the majority of children does get their vaccinations. That’s the only way to protect him from some very nasty infections. You’re then relying on the group immunity of the majority of the population.
As soon as too many parents decide to not protect their children, group immunity will break down, and most unprotected children will acquire diseases. Depending on the disease, a number of them will die.