That's a great question. I give a lecture to medical students on this every year. If you have an hour, I can take you through all of it.
The reality is that there is the acute problem and a chronic problem. The infection itself results in massive inflammation within the lungs, and the lungs harbour a lot of inflammatory cells. That inflammation, in the short term, becomes very severe and can lead to permanent damage to the lungs. The infection can lead to that problem.
It can be complicated with what we call ventilator-associated complications. When the lungs get inflamed like that, they become very stiff. Lungs are normally very pliable. They're like a balloon: They inflate and deflate very easily. When the inflammation sets in, they become very stiff. When you're trying to drive air into this stiff bag, there's a chance of developing complications like a collapsed lung or a punctured lung. Those are ventilator-associated complications. Those are very well studied, and there are strategies within the ICU to prevent the frequency or occurrence of them, but at the end of the day, there's still a potential risk of ventilator-associated complications.