- Correspondence to Mark Goodchild, World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland;
- Received 10 July 2016
- Revised 26 October 2016
- Accepted 18 November 2016
- Published in print 4 January 2017.
- Published online 30 January 2017.
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.