1. Brighton and Sussex Medical School Department of Global Health and Infection, University of Sussex, 94 N–S Road, Falmer, Brighton BN1 9PX, UK
2. The Royal Sussex County Hospital, University Hospitals Sussex NHS Foundation Trust, Eastern Road, Brighton BN2 5BE, UK
3. Department of Anaesthetics, King’s College Hospital NHS Foundation Trust , Denmark Hill, London SE5 9RS , UK