In one of their radio shows, Meltzer/Alvarez said when traveling for the Tribute to the Troops with Mysterio & Jack Doane, Ron Killings went into convulsions and they got him to the hospital. Supposedly, the doctor said had they gotten him there later or not at all, he likely would have died because there was no oxygen getting to his brain.
He said the convulsions were related to pneumonia and he'll be out of action for a couple weeks till that passes.
Luckily, he was with people.