Bernadette Purcell a
These authors contributed equally to this work.
Kent Surrey and Sussex Public Health England Centre, County Hall North, Chart Way, Horsham, West Sussex RH12 1XA, UK
Gavin Dabrera ⁎, a
These authors contributed equally to this work.

Field Epidemiology Training Programme, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK
European Programme for Intervention Epidemiology Training, European Centre for Disease Control and Prevention, Stockholm, Sweden
Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK
Araceli Busby, Alison Mason
Kent Surrey and Sussex Public Health England Centre, County Hall North, Chart Way, Horsham, West Sussex RH12 1XA, UK
Koye Balogun, Sema Mandal
Centre for Infectious Disease Surveillance and Control, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK
Siew-Lin Ngui
Virus Reference Department, Microbiology Services, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK