The patients are being treated at 21 medical facilities across the country.

The health ministry said 52 patients have tested negative once and 23 others have done so between two and four times.

Among those testing negative for the first time are two British tourists being treated at the Hue Central Hospital in the central province of Thua Thien-Hue.

One patient was confirmed positive for the Covid-19 virus on March 8 while staying in Hue. She’s the wife of another patient who was discharged on March 31 and is being monitored at a local resort.

The other British patient is a 49-year-old man who’d flown in from London on March 2. The man was confirmed infected with the virus on March 9.

The ministry also revealed two of five critically ill patients, a 64-year-old Vietnamese woman and a 69-year-old British man, have tested negative three times in a row but are being closely monitored. They are being treated at the National Hospital of Tropical Diseases in Hanoi's Dong Anh District.

Particularly noteworthy is that the woman, who’d experienced breathing difficulties that escalated into respiratory failure on March 15, has stopped using the life support machine called Extracorporeal Membrane Oxygenation (ECMO) since Saturday.

Another critically-ill British patient, 74, has tested negative four times.

Under Health Ministry regulations, a person infected with the novel coronavirus is deemed healthy once she/he shows no sign of fever for three days and tests negative twice in three days. Other signs include improved clinical symptoms, overall stable status and vital signs, normal organ function and improved chest X-ray readings.

Vietnam has only reported one new coronavirus infection in the past 24 hours - a 20-year-old man in HCMC returning from the U.K. So far, 91 patients have been discharged from hospital.

Many of the 150 active cases are Vietnamese nationals returning from abroad, mostly from Europe and the U.S., and more than 60 people are related to the two major Covid-19 hotspots in the country – the Bach Mai Hospital in Hanoi with at least 43 cases and Buddha Bar & Grill in Ho Chi Minh City 18 cases.

The global death toll in the ongoing Covid-19 pandemic has reached more than 69,300 people.