Hanoi should prepare medical equipment and materials for another "fight against COVID-19", the Southeast Asian country's government said in a statement, which made no mention of the case reported in media.

Thanks to a centralized quarantine program and an aggressive contact-tracing system, Vietnam had managed to keep its coronavirus tally to just 446 cases, despite sharing a long and porous border with China.

Vietnam, with over 95 million people, is the most populous country in the world to have recorded no deaths from the virus.

That record is now under threat following an outbreak last weekend in Danang, where tens of thousands of local tourists had been taking advantage of heavily discounted travel deals designed to support the country's virus-hit tourism industry.

The government on Tuesday suspended all flights to and from Danang for 15 days. At least 30 cases of the novel coronavirus have been detected in or around the city.

About 18,000 tourists who had been in Danang have returned to the southern business hub Ho Chi Minh City, authorities said on Tuesday.

The Hanoi authorities had earlier said they were expecting 15,000 to 20,000 to return for Danang.

A staff member at a Hanoi pizza restaurant who recently returned from Danang had tested positive for the coronavirus, state media reported on Wednesday, adding that authorities had closed the restaurant for disinfection.

The health ministry has yet to confirm a new Hanoi case.

Vietnam will repatriate 120 construction workers infected with COVID-19 from Equatorial Guinea on Wednesday, according to state media. The stricken workers will be treated at a hospital outside Hanoi.