Published on in Vol 9, No 11 (2021): November
This is a member publication of The University of Edinburgh, Usher Institute, Edinburgh, United Kingdom
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/32093, first published
.

1 Centre for Population Health Sciences, Usher Institute, University of Edinburgh , Edinburgh , GB
2 Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine , London , GB