Received: 6 April 2019
Accepted: 30 July 2019
First Online: 7 August 2019
Ethics approval and consent to participate
: Approved by the Medical Research Ethics committee of the University Hospitals Leuven (MP001492). Written informed consent was obtained from all participants, or a parent or guardian for participants under 16 years old.
: Not Applicable
: The authors declare that they have no competing interests