Obviously enough, the hospital tried to delay announcing the deaths that occurred and gather as much data as possible, but it didn't take long before they discovered that "Jolene" still had brain activity despite being declared dead due to her internal organs getting punctured from the inside and out.
The brain was supposed to have activity for around four to six minutes as a person died and something thought impossible became possible… in a sense.
At that point, the term "zombification" wasn't even in their heads yet because the words brain and skeletal auto-regeneration were being thrown around—in their words, the brain's ability to stay alive and "jump" the rest of its body like a car would so it would be able to function as normal again.