Medical staff prepare to disinfect the neighborhood of a Covid-19 patient in Phan Thiet, Binh Thuan Province, south central Vietnam, March 10, 2020. Photo by VnExpress/Viet Quoc.

The 51-year-old patient, a resident of the south-central Binh Thuan Province, had flown from Ho Chi Minh City to New York on February 22, transiting at Incheon International Airport in South Korea for three hours.

On February 29, she flew back from Washington D.C., transiting at the Doha International Airport in Qatar. She landed at Tan Son Nhat Airport in HCMC on March 2 and took a car home to Phan Thiet resort town in Binh Thuan.

On March 5, she developed high fever and cough. Four days later, she was admitted to the Binh Thuan General Hospital and placed under quarantine pending Covid-19 tests, and the results came back positive.

Local authorities have identified 17 people who'd come into direct contact with the woman and placed them in isolation.

The Binh Thuan patient is the third case confirmed on Tuesday in Vietnam. The two others are a 24-year-old Vietnamese woman who'd met Nguyen Hong Nhung, Hanoi's first Covid-19 patient, at a party in London last month before falling sick and being put on a private plane to Saigon on Monday, and a British man who boarded the same flight as Nhung from London to Hanoi on March 2.

Since Friday, Vietnam has recorded 18 new infection cases. After Nhung, 12 people on the same flight - 11 foreigners and one Hanoi man - have tested Covid-19 positive.

Nhung's personal chauffeur and an aunt have also been infected.

A Vietnamese man returning from Daegu, a Covid-19 epidemic epicenter in South Korea, is the other among 18 active cases in the country.

The Covid-19 outbreak has thus far spread to 115 countries and territories around the world, killing over 4,000.