Author information: (1)Public Health Scotland, Meridian Court, 5 Cadogan Street, Glasgow, G2 6QE, UK. Sema.Nickbakhsh@phs.scot. (2)Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK. Sema.Nickbakhsh@phs.scot. (3)Public Health Scotland, Meridian Court, 5 Cadogan Street, Glasgow, G2 6QE, UK. (4)MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow, G61 1QH, UK. (5)School of Computing Science, University of Glasgow, 18 Lilybank Gardens, Glasgow, G12 8RZ, UK. (6)West of Scotland Specialist Virology Centre, NHS Greater Glasgow and Clyde, Glasgow Royal Infirmary, New Lister Building, Glasgow, G31 2ER, UK. (7)Royal Infirmary of Edinburgh, NHS Lothian, 51 Little France Crescent, Edinburgh, EH16 4SA, UK. (8)NHS Greater Glasgow and Clyde, Gartnavel General Hospital, 1055 Great Western Road, Glasgow, G12 0XH, UK. (9)School of Medicine, University of St Andrews, North Haugh, St Andrews, KY16 9TF, UK. (10)MRC-University of Glasgow Centre for Virus Research, 464 Bearsden Road, Glasgow, G61 1QH, UK. Christopher.Illingworth@glasgow.ac.uk. (11)Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, UK. Christopher.Illingworth@glasgow.ac.uk. (12)MRC Biostatistics Unit, University of Cambridge, East Forvie Building, Forvie Site, Robinson Way, Cambridge, CB2 0SR, UK. Christopher.Illingworth@glasgow.ac.uk. (#)Contributed equally