Footnotes

• Handling editor Tristan J Barber

• Contributors PAC conceived the idea for the paper. CTC, BGR, MAM, SCN and PAC contributed to writing the early drafts of the paper. BGR, MAM and SCN reviewed the manuscript drafts and provided feedback. CTC designed the figure. PAC and CTC prepared the final manuscript with contributions from all coauthors. All authors contributed to and have approved the final manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient consent for publication Not required.

• Provenance and peer review Not commissioned; externally peer reviewed.