A tour guide in Hanoi was announced the 39th novel coronavirus disease (COVID-19) patient in Vietnam on Wednesday.
The new case was confirmed by the Ministry of Health in the evening.
The 25-year-old tour guide works for Amazing Ninh Binh Company.
He lives in Cau Giay District, Hanoi.
He was in contact with an infected British visitor who had arrived in Vietnam on March 2 aboard flight VN0054 from London, which was operated by national carrier Vietnam Airlines.
He took the Briton to Ninh Binh Province in northern Vietnam for a vacation, according to national broadcaster VTV.
The neighborhood where the tour guide stays was disinfected on Tuesday night.
The owner of the house he is renting and her child have been taken to a quarantine zone.
The patient suffered a slight fever, no cough, and no shortness of breath. He was hospitalized around 9:00 pm on Sunday.
His test returned positive on Wednesday afternoon.
He is isolated in stable health at the National Hospital for Tropical Diseases in Hanoi.
Forty people who had close contact with the tour guide will be quarantined at hospitals near their places of residence, said Nguyen Khac Hien, director of the Hanoi Department of Health.
About 200 others who were in contact with the forty have been required to self-isolate at home, he added.
Four other patients were confirmed the same day, three of them linked to patient No. 34 in south-central Binh Thuan Province, who returned from the U.S. on February 29. The other case is an employee at a location of Dien May Xanh, a major electronics store chain, in Da Nang.
The Da Nang patient was in close contact with two infected Britons from the same flight VN0054.
Vietnam has confirmed 39 positive cases of the viral infection so far, with 16 having fully recovered and been discharged from the hospital by February 26.
About a dozen cases are traced to patient No. 17, who was diagnosed on Friday last week after Vietnam had reported no new infection since February 13..
She seemed to hide her visits to France and Italy when carrying out immigration procedures at Noi Bai International Airport in Hanoi.
Vietnam requires those arriving from countries where there is a major COVID-19 outbreak to be quarantined in designated zones.
The Southeast Asian country will suspend visa-free travel for eight European countries, including Denmark, Norway, Finland, Sweden, the United Kingdom, Germany, France and Spain, from March 12 over COVID-19 concerns.