Why do people who have never been vaccinated against anything and travel widely not contract grave illnesses?

The power of vaccinations is a fairy story,there is no real evidence that they work,in fact in seems that they are actually very bad for you and interfere with your immune system.Unvaccinated people and children are always much healthier than the vaccinated,also despite the propaganda you'd be very hard pushed to find an unvaccinated child with autism.