Hewitt, J., Carter, B., Vilches-Moraga, A., Quinn, T. J., Braude, P., Verduri, A., Pearce, L., Stechman, M., Short, R., Price, A., Collins, J. T., Bruce, E., Einarsson, A., Rickard, F., Mitchell, E., Holloway, M., Hesford, J., Barlow-Pay, F., Clini, E., … Guaraldi, G. (2020). The effect of frailty on survival in patients with COVID-19 (COPE): A multicentre, European, observational cohort study. The Lancet Public Health, 5(8), e444–e451. https://doi.org/10.1016/S2468-2667(20)30146-8