Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H13-Health-022, H10-Child-020)
Toyama Medical Association (n.p)
Japan Foundation (n.p)
Received: 17 June 2020
Accepted: 10 December 2020
First Online: 6 January 2021
Ethics approval and consent to participate
: Our studies were approved from the Ethics Committee of Toyama Medical and Pharmaceutical University (current University of Toyama). We affirm that informed and written consent was obtained from all children and their parents. Our study was in accordance with the Helsinki Declaration of 1964 and later versions.
: Not applicable.
: The authors declare that they have no competing interests.