Funding for this research was provided by:
the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government (MEXT)/Japan Society for the Promotion of Science (JSPS) KAKENHI (26460820)
Article History
Received: 1 September 2020
Accepted: 10 December 2020
First Online: 4 January 2021
Compliance with ethical standards
:
: This study was carried out after approval by the Ethical Review Committee of the Osaka Prefectural Institute of Public Health (reference number 1310-11-2). Written informed consent was obtained from the parents of all the children before the study.
: The authors declare that they have no conflict of interest.
: Not applicable.