1. 2Immunisation and Countermeasures Division, Public Health England – National Infection Service, London, UK
2. 1Respiratory and Vaccine Preventable Bacteria Reference Unit, Public Health England – National Infection Service, London, UK
3. 3Department of Pathology and Infectious Diseases, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK