"Patient 20", a 64-year-old Hanoi woman who had contracted pneumonia, was brought to the National Hospital for Tropical Diseases in the capital with failing health 54 days ago. She spent 44 days in intensive care. The patient is making a slow recovery and would continue to receive supplementary nutrition and respiratory care before entering rehabilitation and the extracorporeal membrane oxygenation procedure is stopped.

"Patient 161", an 88-year-old woman from the northern province of Hung Yen, is following a similar trajectory. She is receiving treatment at the same hospital in Hanoi.

A British pilot for Vietnam Airlines, "patient 91", still severely ill, is making slow progress at the Ho Chi Minh City Tropical Hospital. The 43-year-old remains on ECMO and artificial ventilation.

Meanwhile, the number of relapses is growing slowly. In Ho Chi Minh City "patient 92" again tested positive for the novel coronavirus on Thursday, 15 days after discharge, bringing the total number of relapses to 12.

Deputy Minister of Health Nguyen Truong Son ascribed relapses possibly to the virus invading and developing in other organs like the lungs and in the digestive system.

Another possible reason is that real-time RT-PCR tests pick up remnants of the virus, but they are not active.

The third possibility involves the capability, sensitivity and specificity of the current RT-PCR technique. In addition to sample quality, its location may also affect test results.

Vietnam recorded no new Covid-19 cases on Thursday, the sixth clean day and the 15th without community transmission.

Of the 270 confirmed cases, 51 remain active while the other 219 have been discharged from hospital.

The Covid-19 pandemic has spread to 210 countries and territories so far, claiming over 233,700 lives