It is possible for a person to build natural immunity against diseases by taking up healthy practices without having to use vaccines. In the other hand, vaccines give you immunity by preexposure to attenuated version of the disease causative organism.
Which is more effective to prevent getting infected by diseases between building immunity naturally or using vaccines?
Sometimes vaccines are very important. You sure can continue to eat natural foods and practice healthy lifestyle to avoid diseases but that might not still not be enough to maintain your good health, especially when there are new pandemics, like the ones we are seeing in recent times.