as far as i know cah has NOTHING to do with the immune system.......as a matter of fact i have cah and hardly ever get sick but when i do i get over it really quick.......chill out!!! and make sure you know all the facts about the disorder before you worry about it......your kid will be FINE and i think it will be fine to not get his meds to him until 4........but you prob want to ask your doc. or pharmacist