Funding for this research was provided by:
Wellcome Trust (100217)
UiT Arctic University of Norway (not applicable)
Norwegian Institute of Public Health (not applicable)
Norwegian Ministry of Health and Social Affairs (not applicable)
Russian program for the state support of leading universities of the Russian Federation "5-100" (not applicable)
Received: 5 August 2019
Accepted: 5 March 2020
First Online: 23 March 2020
Ethics approval and consent to participate
: This study involved the secondary analysis of a small number of variables in anonymized datasets from a variety of sources all of which had obtained ethics approval. No ethical approval is needed to access any data used in this study.
: Not applicable.
: The authors declare that they have no competing interests.