1. Heart of England NHS Foundation Trust, Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK
2. Institute of Microbiology and Infection, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
3. Public Health England Birmingham Laboratory, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK
4. Statistics Unit, Statistics, Modelling and Economics Department, Public Health England, Colindale, London NW9 5EQ, UK