Clark, A., Jit, M., Warren-Gash, C., Guthrie, B., Wang, H., Mercer, S., Sanderson, C., McKee, M., Troeger, C., Ong, K., Checchi, F., Perel, P., Joseph, S., Gibbs, H., Banerjee, A., Eggo, R., Nightingale, E., O'Reilly, K., Jombart, T., Edmunds, W., Rosello, A., Sun, F., Atkins, K., Bosse, N., Clifford, S., Russell, T., Deol, A., Liu, Y., Procter, S., Leclerc, Q., Medley, G., Knight, G., Munday, J., Kucharski, A., Pearson, C., Klepac, P., Prem, K., Houben, R., Endo, A., Flasche, S., Davies, N., Diamond, C., van Zandvoort, K., Funk, S., Auzenbergs, M., Rees, E., Tully, D., Emery, J., Quilty, B., Abbott, S., Villabona-Arenas, C., Hué, S., Hellewell, J., Gimma, A. & Jarvis, C. 2020, 'Global, regional, and national estimates of the population at increased risk of severe COVID-19 due to underlying health conditions in 2020: a modelling study', The Lancet Global Health, 8(8), pp. E1003-E1017. http://dx.doi.org/10.1016/S2214-109X(20)30264-3