Funding for this research was provided by:
Japan Agency for Medical Research and Development (17fk0108108j0601, 18fk0108035j0602, 19fk0108035j0603)
Received: 7 July 2020
Accepted: 16 October 2020
First Online: 23 October 2020
Ethics approval and consent to participate
: The research protocol for establishing the cut-off value of the ELISA using Japanese donors’ sera, and the seroepidemiological protocol using sera from the serum bank of the National Institute of Infectious Diseases, Japan (NIID) were approved by the medical research ethics committee of the National Institute of Infectious Diseases for the use of human subjects (approval no. 1097 and 1069). Before sample collection, written informed consent was obtained from the participants or the participants’ parents. The personal information of clinical specimens was masked. All personal information was anonymised, and no data allowing individual identification was retained. This study was carried out according to the principles expressed in the Declaration of Helsinki.
: Not applicable.
: The authors have declared that no competing interests exist.