A 21-year-old Vietnamese student who'd returned from France was announced Covid-19 free Tuesday evening.

"Patient 92" was confirmed positive on March 21 after returning from Paris and discharged from the Cu Chi Field Hospital in Ho Chi Minh City on April 14.

However, he tested positive again on April 30 and was admitted to the city's Hospital for Tropical Diseases for further treatment.

Since early May, he had repeatedly tested negative.

The hospital announced that he is free from Covid-19, but will be kept under medical monitoring for another 14 days.

So far, Vietnam has recorded 12 Covid-19 relapses of whom six have recovered.

Health experts have said the virus samples taken from relapsed patients are "inactive" and the virus cannot be transmitted to others. They have also said relapsed patients are not given the same dosage of medicines as new fresh Covid-19 patients. Instead, the focus is on monitoring symptoms of the relapse and repeat testing of samples.

Meanwhile, "Patient 91," a British man who has been Vietnam’s most critical Covid-19 case to date, has shown some progress, Nguyen Vinh Chau, director of the HCMC Hospital for Tropical Diseases, said Tuesday.

The most recent computed tomography scan results showed that 20-30 percent of his lungs could now function, compared to just 10 percent a week ago.

However, he is still completely reliant on a life support machine called extracorporeal membrane oxygenation (ECMO), and a lung transplant is still on the agenda, Chau said.

The Health Ministry has announced last week a decision to provide a lung transplant for the 43-year-old patient, who works as a pilot for national flag carrier Vietnam Airlines.

The nation has spent about VND5 billion ($215,000) over the past two months on him, and the estimated cost of a lung transplant is about VND1.5-2 billion ($65,000 to 86,000).

Another obstacle in the case is that the pilot had said he has no relatives when he was still conscious. Under current regulations in Vietnam, all surgical interventions must be agreed to by the patient or the patient's authorised representative.

Vietnam did not record a new Covid-19 patient Tuesday, marking the 33rd day in a row that it has gone without a community infection.

The nation’s Covid-19 tally is 324, including 61 active patients. The rest have recovered.