The 42-year-old, identified only as Patient 16, flew back to South Korea on Jan. 19 after traveling in Thailand, the Korea Centers for Disease Control and Prevention (KCDC) said in a statement.
Treated since developing chills and other symptoms from Jan 25, she did not improve until Sunday, the KCDC added, and was confirmed positive on Tuesday, following checks at Chonnam National University Hospital.
The statement did not explicitly rule out a visit to China, however.