I've gone to the clinic in the Walgreens down the road from Centra Care twice for sinus infections & I go to one when I'm home & get them. They almost never have a wait (I sat in Centra Care with a friend for 4 hours one day). The only downside to Walgreens is if you don't have a car or a friend with a car who is willing to take you, it's kinda far from the apartments. It's probably almost 2 miles from Vista. The closest the busses get to where it is, is when it goes to Crossroads in the evenings, but I think the clinic might be closed by then.
If you get hurt at work, there's health services in the cast parking lot at epcot, but you can only go there if its work-related. There's also the center for living well in the cast lot at epcot, but you have to have disney insurance to go there. (I tried & was turned away cuz I wasn't on disney's insurance plan, even tho I had the same insurance provider, it was just thru my dad's work.)