The answer you receive to any question regarding miracles will depend greatly on the person you are asking. Some will say that miracles occur all the time while others will say that everything has a rational and reasonable explanation, even if finding that explanation is difficult or even impossible depending on the circumstances of the evidence.
It is rather infuriating how people throw around the word "miracle" for things that, if they just look around, aren’t such rare occurrences. Calling a common occurrence a "miracle" is to degrade the word. Babies are conceived and born all the time, yet every baby is called a "miracle". Defying odds is not a miracle. It is merely defying odds. Something occurring for which there is plenty of evidence suggesting that said occurrence is impossible would be a miracle.
In other words, something that is possible, however remote, cannot be a miracle by definition.
So is it correct to call the case of the 21 year-old student who "miraculously" awoke from a coma a miracle? No.
People wake from comas, so the fact 21 year-old Sam Schmid awoke from a coma, into which he fell following a 5-car collision, is unto itself not a miracle. Comas are also still largely a mystery with regard to neurology, and while we can determine with a reasonable degree of certainty if someone is in a coma, judging the degree and whether someone will awaken is a bit difficult. Physicians do misjudge both. So the fact the physicians misjudged the degree of this person’s coma and miscalculated the possibility of waking up is also not a surprise.
Further the age of the patient must also be taken into account – something few appear to be doing. Younger patients tend to be better able to bounce back from injury, often "defying odds" and exceeding physician expectations. Are these events "miracles"? Certainly not. With proper treatments and the necessary degree of immobilization, the human body can repair many injuries it sustains. But there’s the caveat: with proper treatments and the necessary degree of immobilization. And some people can and do heal faster than others.
So what would be a miracle then? Here’s an example: a compound fracture that heals back to normal with no immobilization of the arm and no treatments for any wounds, including the punctures and tears of the bones going through flesh within days instead of weeks. Without treatment there may be some "healing" as the human body will do what it can to repair the damage, but a compound fracture poses an almost certain risk for infection and gangrene, meaning a compound fracture that is not properly treated will almost certainly require amputation. As such a compound fracture in a limb that heals completely with the bone, skin and flesh all returning fairly close to normal with no intervention of any medical nature would itself be a miracle.
However a 21 year-old victim of a 5-car collision coming awake after being in a coma for the better part of 2 months isn’t a miracle, as the article describing the student’s injuries states plainly (emphasis added):
For days Schmid didn’t seem to be responding, but what puzzled his doctor was that he did not see fatal injuries on the MRI scan. So he decided to keep Schmid on life support longer.
"There was plenty wrong — he had a hemorrhage, an aneurysm and a stroke from the part of the aneurysm," Spetzler said. "But he didn’t have a blood clot in the most vital part of his brain, which we know he can’t recover from. And he didn’t have a massive stroke that would predict no chance of a useful existence."
In other words, despite the fact he was not being responsive, there was still an expectation of recovery. But that expectation does dwindle as time goes on: the longer a patient is comatose, the less likely they are to awaken. A comatose patient could also slip into what is called a "persistent vegetative state", out of which recovery and awakening to consciousness is very rare.
Further the MRIs were showing that Sam’s body was recovering, healing itself from the inside after doctors intervened to repair the most life-threatening injuries:
So while the family was given a realistic picture of Schmid’s poor chances for survival, Spetzler ordered one more MRI to see if the critical areas of the brain had turned dark, indicating brain death.
The MRI came back with encouraging news during the day and by evening Schmid "inexplicably" followed the doctors’ commands, holding up two fingers.
Again this isn’t a miracle. The fact he is doing so well after waking shows that the coma served a purpose: the brain gave the body a chance to heal itself.
But what is even more disconcerting about calling this person’s recovery a miracle is simply this: if it truly is a miracle, it isn’t one that proves a point. It isn’t evidence for any god, especially the god of the Bible. If the god of the Bible were to perform a miracle that could be seen by anyone as being a miracle, then instead of waking a comatose patient, wake one that is unmistakably dead, say in the casket in front of the congregation during a funeral.
Or even better, cure a little girl for whom recovery has been deemed impossible. You see on Monday, December 19, 2011, a little girl of the tender age of three years old died of leukemia. I know her only as Sidney Mae. She spent much of her short life in a hospital. Her grandfather is also a rather prominent atheist, well known among atheists all across the country. Why wake a 21 year-old comatose patient when you could cure a 3 year-old of her leukemia and likely convert an atheist in the process?
Why call the awakening of a 21 year-old car accident victim a "miracle" when a true miracle to be performed that would have undeniably shown the existence of a higher power would have been to heal a little girl who’d been suffering with cancer for much of her very short life?
Sam’s recovery was remarkable, to say the least, but a miracle it was not for one clear reason: miracles do not happen.