Unfortunately, that is absolutely not even possible. You could use every vaccination known for avians, be out quite a lot of money, and still not be able to do what you just stated. Just for an example, did you know there are 9 named/known types of coccidiosis, and yet, I know of mutated, unnamed types that pass down from the parent stock through the egg to the chick and do not have the usual signs we normally look for?
Did you know that there is a disease called Spotty Liver Disease, rare, but seeing a resurgence, caused by a bacteria they have not even reliably determined yet as to exactly what it is, mainly pops up in free range flocks in their prime and there is no vaccination for that? So, there are
many bacteria that you simply cannot defend against.
You can raise your birds any way you see fit, of course, but the above statement you made is just not possible. I've never vaccinated my birds for anything, ever, and never had any contagious disease in my free range flocks. If you want to spend hundreds of dollars on vaccinations, that is of course, your choice, but it's simply not what 99% of most chicken keepers do.
Since this is the Buff Orpington thread, though, I think we should get back on the main subject.