Doctors wear protective gears before going into the quarantine room at a hospital in Saigon, March 2020. Photo by VnExpress/Quynh Tran.

The 27-year-old chauffeur and the 64-year-old aunt of 26-year-old Nguyen Hong Nhung, who had tested positive for the novel coronavirus Friday, are residents of Truc Bach Street in Ba Dinh District and were in close contact with her.

Both were identified as being at high risk of contracting the infection from Nhung. Tests ordered by health authorities confirmed they are the 19th and 20th Covid-19 infection cases in the country.

25 others in close contact with Nhung had earlier tested negative for the coronavirus. Hundreds of people who might have come in contact with Nhung have been quarantined and are being closely monitored.

Vietnam has recorded four new infections within 24 hours after Nhung became Hanoi’s first Covid-19 patient in Hanoi and the 17th nationwide. Before she tested positive for the virus, the country had gone 22 days with no new infection.

The Health Ministry had on Saturday afternoon confirmed the 18th infection, a 27-year-old man who has been quarantined in northern Ninh Binh Province upon returning to Vietnam from Daegu City in South Korea since Wednesday.

Nguyen Hong Nhung had left Hanoi's Noi Bai Airport on February 15 to visit family members living in London, England. Three days later, she traveled from London to Milan City, in the province of Lombardy, Italy, and returned to London on February 20.

During her time in Milan, Lombardy had not recorded any Covid-19 positive case.

On February 25, the woman traveled from London to Paris to visit her sister. She contracted a cough on February 29, but did not get checked up.

On March 1, she reportedly felt body pain and fatigue, but it was unclear if she had a fever. The same day, she boarded flight VN54 of Vietnam Airlines from London and landed in Hanoi at 4:30 a.m. on March 2. She did not have a fever then.

After completing entry procedures, the patient was allowed to drive a family car home to Truc Bach Street in Ba Dinh District’s Truc Bach Ward.

Later, she developed a mild fever and coughed a lot, and was admitted to Hong Ngoc Hospital in Ba Dinh District Thursday. The very same day, she was transferred to the Central Hospital for Tropical Diseases where she tested positive for the novel coronavirus.

Flight VN54 carried 201 passengers, and authorities are in the process of verifying their names and whereabouts.

Saying that Hanoi has the highest risk of hosting an outbreak as residents of almost all 90 countries and territories hit by the new coronavirus so far are now living and working in the city, Hanoi Chairman Nguyen Duc Chung said: "I urge everyone to be aware of the risks of infection and how dangerous the epidemic is. Everyone returning to Vietnam from abroad needs to report themselves to the authorities and follow quarantine protocol as regulated.

All 16 persons confirmed with Covid-19 infections in Vietnam earlier have been discharged from the hospital.

The Covid-19 epidemic has spread to 100 countries and territories around the world with global death toll climbing to 3,500.

Starting Saturday, everyone coming to Vietnam have to fill health declarations.