Critical care staffing ratio and outcome of COVID-19 patients requiring intensive care unit admission during the first pandemic wave: a retrospective analysis across Switzerland from the RISC-19-ICU observational cohort - Marie-Madlen Jeitziner; André Moser; Pedro D Wendel-Garcia; Matthias Thomas Exl; Stefanie Keiser; Reto A. Schuepbach; Urs Pietsch; Sara Cereghetti; Filippo Boroli; Julien Marrel; Anne-Aylin Sigg; Hatem Ksouri; et al. (Swiss Medical Weekly, 2022)