Sick calls get covered anyway they can be covered. Most of the bases have some reserve, not entire lines but reserve here and there. There's probably always someone on reserve somewhere in the system so as long as you don't call in sick an hour before your flight you won't get beat with the scheduling stick.
Full medical is available, something around $150 I think, not sure I have medical from my sugar momma.
Any more questions feel free to ask or search for colgan, lots of info already here, disregard the crap from the haters...