Funding for this research was provided by:
Economic and Social Research Council (ES/J500021/1)
Text and Data Mining valid from 2019-06-20
Received: 6 December 2018
Accepted: 11 June 2019
First Online: 20 June 2019
Ethics approval and consent to participate
: The analysis of secondary data was approved by the London School of Hygiene and Tropical Medicine’s Research ethics committee (ref: 12097). We obtained approval from Measure DHS to access the data.
: Not Applicable.
: The authors declare that they have no competing interests.