- 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 in print 1 December 2017.
- Published online 7 November 2017.
- Published first 22 October 2017.
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