About the Authors
Centre for Public Health Research, Brunel University, Uxbridge, United Kingdom
LSE Health, London School of Economics, London, United Kingdom
Save the Children UK, London, United Kingdom
The authors have declared that no competing interests exist.
ICMJE criteria for authorship read and met: DDR CMM JWM PA. Wrote the first draft of the paper: DDR. Contributed to the writing of the paper: CMM JWM PA.