Funding for this research was provided by:
Seventh Framework Programme (603946)
Received: 22 July 2020
Accepted: 17 January 2021
First Online: 4 February 2021
Ethics approval and consent to participate
: Ethical approval was received for each study centre (UK: Heriot Watt University Ethics Review Board 2015–07, London School of Hygiene and Tropical Medicine Observational / Interventions Research Ethics Committee 17028; Netherlands: Medisch Ethische Toetsingscommissie Brabant NW2015–07; Athens: National Centre for Scientific Research ‘Demokritos’ Ethics Review Board 2015–04: 260/2015–1671; Thessaloniki: Aristotle University Ethics Committee 140540/2018). Informed written consent was provided by all participants.
: Not applicable.
: The authors declare that they have no competing interests.