1. Public Health England Food Water and Environmental Microbiology Services, National Infection Service, Colindale, London, NW9 5EQ, UK (ORCID: https://orcid.org/0000-0003-0516-7873 [J.M.]; https://orcid.org/0000-0001-9693-7700 [N.E.])
2. Public Health England Food Water and Environmental Microbiology Laboratory York, National Infection Service, York Biotech Campus, York, YO41 1LZ, UK
3. Public Health England Statistics, Modelling and Economics Department, National Infection Service, 61 Colindale Avenue, London, NW9 5EQ, UK (ORCID: https://orcid.org/0000-0001-7154-0432 [A.C.])
4. Public Health England Food Water and Environmental Microbiology Laboratory Porton, National Infection Service, Porton Down, Salisbury, SP4 0JG, UK