Received: 31 January 2021
Accepted: 11 July 2021
First Online: 15 July 2021
: This study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Review Board (IRB) of Beijing Children’s Hospital, Capital Medical University.
: All authors have read and approved the final manuscript. All parents signed informed consent forms and approved the final manuscript.
: The authors declare that they have no competing interests.