- Correspondence to Dr Benjamin J Gray, Policy, Research and International Development, Public Health Wales, Cardiff, CF10 4BZ, UK;
- Received 17 August 2017
- Revised 18 September 2017
- Accepted 25 September 2017
- Published online 7 November 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.