Then would suggest that you just try to keep a close eye for any symptoms, so you catch it early. Coccidiosis is common, but it doesn't happen to every batch of chicks. If you have Corid on hand then you can be ready to treat right away if you do see any symptoms. When I raise chicks in a brooder I don't use medicated feed. I keep things as clean and dry as I can (chicks are messy) and I give them a dish of soil from outside starting in the first few days of life. I use a large plant saucer. Easy to dump and clean, and refill with clean soil. They scratch and dig and dustbathe in it (they LOVE it) and it exposes them naturally to the microbes in the soil, giving them a chance to build immunity naturally (same as a broody hen raised chick would). I keep meds on hand in case they are needed. But exposing them this way from very early has cut my incidence of outbreaks to almost nil (I havent' had an outbreak going on 7 years now). If I ever had an outbreak of a very virulent strain, or had lots of outbreaks, I might consider using medicated feed. But it hasn't been necessary in my flock and I prefer not to give meds unless they are really needed. There really isn't one right answer for all flocks, your environment and how you keep and manage your flock makes every situation different.