The quarantine area at the Hospital of Tropical Diseases in Ho Chi Minh City, March 2020. Photo by VnExpress/Huu Khoa.

The man went to the Ho Chi Minh City Center for Disease Control to report that he had come into contact with an infected businesswoman in Binh Thuan Province.

He worked with the woman and her husband, and had dinner with them in the south central province on March 3. He returned to Saigon the next day in a private car with three others.

On March 10, after learning that the businesswoman had tested positive for the virus, he isolated himself at home. On March 12, he developed symptoms of a stuffy nose and sore throat; and went to the district health center to get it checked.

He was quarantined at the health center before being taken to the Cu Chi field hospital for centralized quaratine in outlying district Cu Chi in a specialized ambulance.

His samples were tested at the city's Hospital of Tropical Diseases and the results came back positive Thursday night for the first time. The samples were taken to the Pasteur Institute in Ho Chi Minh City Friday to double check. The infection was confirmed the same day.

Health officials have investigated and quarantined those who’d coming into close contact with the man. They also disinfected his home and neighborhood.

The businesswoman, 51, had flown from Ho Chi Minh City to New York on February 22, transiting at the 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 the Tan Son Nhat Airport in HCMC on March 2 and took a car home to the resort town of Phan Thiet in Binh Thuan.

On March 5, she developed high fever and a cough. Four days later, she was admitted to the Binh Thuan General Hospital and placed under quarantine pending Covid-19 tests. She was confirmed positive on Tuesday.

On Thursday, the 59-year-old husband, 28-year-old son, two-year-old granddaughter, an in-law and 12-year-old neighbor boy of the woman also tested positive. A day earlier, her house-help, an employee and daughter-in-law were confirmed infected.

So far, Binh Thuan has recorded nine infection cases, making it the worst hit locality in the country.

Two streets in Phan Thiet have been locked down since Friday as nine people in the area tested Covid-19 positive.

Vietnam has recorded 29 infection cases over the past week, according to the health ministry's data, after going 22 days with no new infections. All 16 Covid-19 patients recorded until then had been discharged from hospitals by February 26.

The Covid-19 outbreak has thus far spread to 127 countries and territories around the world, killing close to 5,000.