One comment that I will never forget was a doctor telling me that when you're sick, the worst place to be is in the hospital. At first, this statement made absolutely no sense. But this doctor went on to explain that, in a hospital, there are germs all over the place. If you are sick, your immune system may not be able to fight off all of the other germs in the hospital.
Since hearing this comment, there have been a number of studies that have indicated that thousands of people a year die in hospitals from bacteria or germs that are not related to the original problem that resulted in hospital confinement. Hence, if they weren't in the hospital, they may not have died.