Funding for this research was provided by:
The Research Council of Norway (229020)
Regionale forskningsfond Oslofjordfondet (245807)
Regional research fund, western Norway (235707)
The Norwegian Directorate of Health (11/751-38 and 14/4285-3)
Received: 10 January 2021
Accepted: 26 April 2021
First Online: 7 May 2021
: The authors have no financial or non-financial interests to disclose.
: The study was approved by the Regional Committee for Medical and Health Research Ethics in Western Norway (no. 2013/2331). Written informed consent/assent was given by caregivers/adolescents.