Publication Type: Journal Article Authors: Forbes, H.; Douglas, I.; Finn, A.; Breuer, J.; Bhaskaran, K.; Smeeth, L.; Packer, S.; Langan, S. M.; Mansfield, K. E.; Marlow, R.; Whitaker, H.; Warren-Gash, C. Source: Bmj, Volume 368, p.l6987 (2020)