Published on in Vol 9 , No 7 (2020) :July
Preprints (earlier versions) of this paper are available at https://preprints.jmir.org/preprint/17779, first published .
1 Kings College London, London, GB
2 Marie Stopes International Cambodia, Phnom Penh, KH
3 London School of Hygiene and Tropical Medicine, London, GB
4 School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, JP
*these authors contributed equally