Received: 24 October 2019
Accepted: 30 March 2020
First Online: 4 April 2020
Ethics approval and consent to participate
: The study was approved by the SNUH Institutional Review Board (1612–061-813) and was registered at ExternalRef removed (NCT03074968, Feb 26, 2017, ExternalRef removed). Each participant and corresponding parent were given a verbal explanation with an opportunity to ask questions about the study. Written informed consent was obtained from participants > 7 years of age and their parents. Verbal assent was obtained from participants < 7 years of age, in addition to written informed consent from their parents.
: Non applicable.
: The authors declare that they have no competing interests.