Yeah, if they're not vaccinated, you'll have to give medicated food. Cocci is devastating and very easily transmitted. It's not worth losing them all.
I feed mine unmedicated, especially my broilers, and that is why I get the vaccination. A vaccination is preventative and will not taint your meat. Sick chickens needing medicine and antibiotics will, and could even push back your butchering schedule (if applicable) because of necessary withdrawal period. Same with certain drugs and eating the eggs. I also make a point of practicing good sanitation as well. Very important.
Your chick starters are usually medicated (check the label) and when you switch to a grower/developer, you are done with that phase because the medicated starter helps them as they develop their own resistance to cocci. The vaccination does the same, only quicker.
Another thing to consider is that some vaccinations like the one for cocci are only efficable if given before 2 days old, after that, too late to get it. IMO, it's really worth it to get them vaccinated.