The patients, coughing and suffering chest pains, were hospitalized from Sunday to Thursday after returning to Lao Cai from trading in China.

All were subsequently quarantined and placed under observation, with blood samples sent for testing to determine whether their symptoms were related to a new coronavirus (nCoV) that started sickening people in Wuhan, China, last December.

On Thursday morning, one patient tested negative for the nCoV virus, with five others have recovered from high fever. The remainder are still being closely monitored.

The virus has spread from mainland China to Hong Kong, Macao, Thailand, Singapore, Taiwan, Malaysia, Japan, Australia, the U.S., South Korea, France, Germany, Canada, Vietnam, UAE, Nepal, Cambodia and Sri Lanka.

Chinese authorities said 170 people had died of the disease as of Thursday morning. The number of confirmed infections has topped 7,700.

The Lao Cai tourism department Monday asked local travel companies to temporarily halt trips to and from China via its land border to prevent the spread of the deadly virus.

To avoid the disease from spreading, some border gates in Lao Cai and the nearby Lang Son Province will remain closed till February 8.

Lao Cai, home to popular tourist town Sa Pa, shares its northern border with China's Yunnan Province.

No Vietnamese has contracted the new coronavirus yet, with the two confirmed victims being Chinese nationals.

Li Zichao, 28, one of two, recovered by Tuesday morning. But his father remains on a ventilator, doctors at Cho Ray Hospital in HCMC said Wednesday.

The government has deployed various measures to combat the virus, including keeping out tourists from China’s epidemic-hit areas and quarantining Chinese workers returning to Vietnam after Tet.

As of Thursday Vietnam reported 97 suspected cases with signs of fever and coughing, all from affected areas. Of these, 32 are in quarantine pending test results.