A .22 rifle does not have sufficient power to kill a deer humanely or quickly by shooting it in the vitals the way most hunters would do with a high-powered rifle. A .22 does however have enough power to completely penetrate a deer's skull. This is why you would take head shots at a deer with a .22 if you are faced with a survival situation.
Remember, "survival should never be political" as I always like to say.
Survival is never pretty. What's most important is that you come out alive.