- Correspondence to Professor Helen Ward, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College, Norfolk Place, London W2 1PG, UK; .
- Received October 19, 2013
- Revised March 2, 2014
- Accepted March 3, 2014
- First published March 31, 2014.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.