Funding for this research was provided by:
Korea Centers for Disease Control and Prevention (2019E520201)
Received: 4 March 2020
Accepted: 12 June 2020
First Online: 23 June 2020
Ethics approval and consent to participate
: This study was conducted in accordance with the Declaration of Helsinki. The Institutional Review Board of the Catholic Medical Center, the Catholic University of Korea approved the study protocol (XC19REDE0040) and waived the need for informed consent because no patients were at risk.
: Not applicable.
: The authors declare that they have no competing interests.