Foreign tourists are sent to quarantine in Ha Long Town of Quang Ninh Province on March 7, 2020 as they are found to board the same flight with a Covid-19 patient in Hanoi. Photo by VnExpress/Giang Chinh.

Of the nine, seven are British, one Irish and one Mexican, aged between 58 and 74. All have been quarantined.

The latest confirmed Covid-19 case, a 66-year-old British woman, has been quarantined in the central town of Hue since Saturday. She is in stable health with no fever or cough.

The remaining eight foreigners were touring Vietnam when they were tracked down by local authorities on being informed that they were passengers on the same flight as Nguyen Hong Nhung, who tested Covid-19 positive Friday.

Four of them were intercepted in Quang Ninh Province, two in Lao Cai Province in northern Vietnam and two in the central city of Da Nang.

Nhung, 26, who had flown to Hanoi from London on Vietnam Airlines flight VN54, became the capital city's first Covid-19 patient and the nation’s 17th.

There were 201 passengers on the flight, including 21 in the business class, Vietnam Airlines General Director Duong Tri Thanh said Saturday. Of the 21, 18 were foreigners.

The nine new Covid-19 cases take the national total to 30.

On Sunday, it was confirmed that a 61-year-old Hanoian on the same flight as Nguyen Hong Nhung had contracted the novel coronavirus. The man, the nation’s 21st Covid-19 infection, lives in the same neighborhood as Nhung in Ba Dinh District.

City authorities have been working with Hanoi’s Noi Bai Airport to collect information about 217 passengers and crew members on the flight.

Before Nhung was confirmed as the 17th Covid-19 patient in Vietnam, the country had gone 22 days with no new infection.

On Saturday, a 27-year-old man returning to Vietnam from South Korea’s Daegu City became the 18th while Nhung’s personal chauffeur and her aunt were the 19th and 20th cases.

The Covid-19 outbreak has thus far spread to 103 countries and territories around the world, with the death toll climbing to 3,649.