HANOI (BLOOMBERG) - An outbreak of four coronavirus cases tied to a Vietnam Airlines flight from London to Hanoi triggered hoarding in the South-east Asian country's capital, the lockdown of a central city neighbourhood and the home quarantine of an investment minister aboard the aircraft.

A growing sense that the virus may be bypassing Vietnam, which had not reported an official case in more than three weeks, was shattered after a 26-year-old Hanoi woman, who landed at Noi Bai International Airport on March 2, tested positive for the virus.

She had visited London, Milan and Paris, the Ministry of Health announced on Friday night (March 6). The government immediately quarantined five acquaintances of the woman.

Over the weekend, the woman's uncle and family driver also tested positive and a 61-year-old man on flight VN0054 - who, like the 26-year-old woman, sat in business class - was confirmed to have the virus, the ministry said. The government immediately quarantined 50 people who had close contact with the 61-year-old man at home and in hospitals.

Planning and Investment Minister Nguyen Chi Dung, who sat in Seat 1A - the first patient sat in Seat 5K - had self-quarantined at home for 14 days after testing negative for the virus. The minister's headquarters were also disinfected, the government announced on its Facebook page.

Of the more than 200 passengers on the flight, 28 were in business class, according to the government. The flight's crew and ground staff are also in isolation, according to the health ministry's news website, Suc Khoe Doi Song. Thirty-two of the passengers on board the aircraft journeyed on to nine different cities in the country, including Ho Chi Minh City, Danang and Phu Quoc.

Vietnam is notifying officials in Europe and elsewhere about the airline virus case and foreign passengers on board, the government said in a statement, citing Ministry of Foreign Affairs spokesman Le Thi Thu Hang.

The sudden spread of the virus unnerved Vietnamese, who rushed to supermarkets to buy rice, meat and other food across Hanoi over the weekend as police and members of the military quarantined the woman's neighbourhood, disinfecting streets in the wealthy enclave a few kilometres from the National Assembly.

The rush to stores triggered a surge in prices of pork - the nation's main source of protein - among traders, from 300,000 dong (S$17.80) per kg to 400,000 dong (S$23.70) per kg, Saigon Giai Phong news website reported.

Prime Minister Nguyen Xuan Phuc ordered government agencies to ensure food suppliers are kept markets well stocked, according to a statement on the government's website posted late Saturday. Officials will inspect markets to investigate possible price gouging.

Hanoi party chief Vuong Dinh Hue, speaking at a conference on Saturday, proposed cancelling large gatherings, such as festivals, and said he was worried about the virus spreading among shoppers waiting in long supermarket lines, Saigon Giai Phong reported.

The four patients, in addition to another unrelated case reported Saturday, gives Vietnam a virus case tally of 21, 16 of whom have recovered, according to the Health Ministry.