Funding for this research was provided by:
Health and Family Planning Commission of Heilongjiang Province (2017-234)
National Natural Science Foundation of China (81872614)
Received: 21 May 2020
Accepted: 17 November 2020
First Online: 2 December 2020
Ethics approval and consent to participate
: The study was conducted in accordance with the Declaration of Helsinki. Consent to participate was obtained from the parents/ guardians of the minors included in this study (minors are considered anyone under the age of 16). The protocol was approved by the Ethics Committee of Harbin Children’s Hospital on May 17, 2016 (No. HRYLL 201605).
: Not applicable.
: The authors declare that they have no competing interests.