Funding for this research was provided by:
Horizon 2020 Framework Programme (733280)
Fundação para a Ciência e Tecnologia (UIDB/04750/2020)
Received: 2 October 2020
Accepted: 29 December 2020
First Online: 12 January 2021
Ethics approval and consent to participate
: The study was approved by the Danish Ethical Committee System and Danish Data Protection Agency in Denmark, the Ethics Committee of Bambino Gesù Paediatric Hospital in Italy, and the Ethics Committee of the Institute of Public Health of the University of Porto and Data Protection Authority in Portugal. Consent to participate was obtained by all participants through explicit written consents according to the data protection policy of the General Data Protection Regulation [(EU) Regulation 2016/67].
: Not applicable.
: The authors declare that they have no competing interests.