Which country for the first time has claimed to use the antibody test to track coronavirus infections?

Which country for the first time has claimed to use the antibody test

1.	Which country for the first time has claimed to use the antibody test to track coronavirus infections?
Answer» In what appears to be a first, disease trackers in Singapore have used an experimental antibody test for COVID-19 to confirm that a suspected patient was infected with the coronavirus. The patient was one of two people who together formed a missing link between two clusters of cases that each occurred in a Singaporean church.