in on study, 24/26 of pts with non-invasive mech ventilation and 31/32 of pts with invasive ventilation died.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
note that the study demographics were skewed to the more vulnerable cohorts (avg age = 56, range = 46-67, 62% male, 48% with a comorbidity).