van Bunnik, B., Morgan, A., Bessell, P., Calder-Gerver, G., Zhang, F., Haynes, S., Ashworth, J., Zhao, S., Cave, N., Perry, M., Lepper, H., Lu, L., Kellam, P., Sheikh, A., Medley, G. & Woolhouse, M. 2021, 'Segmentation and shielding of the most vulnerable members of the population as elements of an exit strategy from COVID-19 lockdown', Philosophical Transactions of the Royal Society B: Biological Sciences, 376(1829), article no: e1962. https://doi.org/10.1098/rstb.2020.0275