Funding for this research was provided by:
Beijing Municipal Science & Technology Commission (Z171100001017081)
Received: 1 February 2020
Accepted: 20 May 2020
First Online: 1 June 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Capital Institute of Pediatrics-Peking University Teaching Hospital (no. SHERLL2019061). All data collected were stripped of patient identifiers, with no possibility to track the data to an individual person’s identity. The data in the study were obtained with the permission of the Capital Institute of Pediatrics-Peking University Teaching Hospital.
: Not applicable.
: The authors declare that they have no competing interests.