The ministry has requested the central city to make a list of all people in close contact with the suspected case. On Thursday night, all of them were tested and the results came back negative.

But they will be quarantined as a safety measure for the community. Also Friday, a group of experts from Hanoi arrived to assist Da Nang with the quarantining process.

The patient suspected of carrying the virus was suffering from acute pneumonia with severe symptoms worsening rapidly. He has been put on a ventilator.

"We have taken an unprecedented measure, which is to conduct testing at high-risk areas in Da Nang by using antibody tests with a Vietnamese-made test kit," acting Health Minister Nguyen Thanh Long said at a Friday meeting of the National Steering Committee for Covid-19 Prevention.

The ministry has also activated a tracking system for people who have come into contact with the patient, he added.

Deputy Prime Minister Vu Duc Dam requested all functional forces, especially health units, the army and the police to up their awareness and stand ready to respond to new pandemic-related developments.

Deputy Minister of Foreign Affairs To Anh Dung said Vietnam has so far organized about 60 repatriation flights, bringing about 15,000 citizens abroad back to the country.

The Steering Committee for Covid-19 Prevention in Da Nang announced the suspected case Friday noon, a 57-year-old retired man living with his wife, daughter and husband and a 18-year-old grandson in Lien Chieu District.

Minister Long said more tests were needed before a Covid-19 diagnosis for the Da Nang man can be confirmed. The National Institute of Hygiene and Epidemiology is expected to announce the result Saturday morning.

In the recent months, he has not left Da Nang, went to three healthcare facilities and attended a wedding in Hai Chau District. On the morning of July 20, he visited Hospital C in Da Nang with fever, cough and phlegm.

Da Nang, which has not recorded a single Covid-19 case since April 10, remains a major attraction for domestic tourists.

Vietnam has gone 99 days without community transmission of the novel coronavirus.