I'm a scientist working on a very high-class operation in a classified area, we experienced some very strange encounters with the people we test on, like trying to bite us, attack us causing harm i think we discovered something.

The most important first realization is to find out if the patients are deceased and their bodies are acting under an outside volition such as a virus reanimating the body through the use of the brain stem. If they are still living then they are what would be called infected if dead they are the undead naturally enough. Keep them contained as best you can but knowing scientists they will get free. When facing an infected they can die to any injuries that a normal human can they just won't react to pain so don't shoot for the head blast that thing in the chest then hit it in the head while it's down. Forget hand to hand combat or most close-ranged weapons unless absolutely necessary because close contact means exposure to fluids from the zombie they don't have to bite you to turn you. There is so much more to be said about this I recommend picking up the ZAS zombie survival book I recently got it and have not yet finished it but have learned a great deal.  

Explanation:

Yes I fully understand this is not real and I simply felt like answering in a detailed manner for fun and that book is a serious recommendation.