I think these 3 paras from the article you found put range of...

I think these 3 paras from the article you found put range of people remestemcel-L can help into perspective, and it still seems to boil down to ARDS;

"But as the pandemic has continued, U.S. hospitals are reporting much lower mortality rates, results on par with death rates for patients with similar severe lung problems caused by other diseases."

"Buhr’s hospital is still putting together data, but he said the mortality rate for ventilated patients is in the 30 percent to 50 percent range. That is about the same as the rate for people who develop acute respiratory distress syndrome, the dangerous buildup of fluid in the tiny air sacs of the lungs caused by diseases such as pneumonia, or injuries such as those suffered in car accidents.

Before the pandemic, about 200,000 people developed acute respiratory distress each year and about 60 percent survived."

No doubt the secondary measures around time on respirator will also be important.