"Patient 251", who tested positive for the virus on April 7, was treated at the National Hospital of Tropical Diseases in Hanoi.
He was discharged from the hospital on April 17 after testing negative four times in a row and transferred to the Ha Nam General Hospital in the northern province of Ha Nam for treatment of liver cirrhosis.
Since March 20, he had been treated at the Ha Nam General Hospital's gastroenterology department for liver cirrhosis, exhaustion and severe gout.
The patient went comatose due to severe impairment of liver function and electrolyte disturbance before his death.
After the patient died, the Ha Nam General Hospital carried out a Covid-19 test and the result came back negative. The patient did not have any symptoms of lung damage caused by Covid-19, doctors said.
On Monday, the Health Ministry discussed the case with leading health experts and confirmed his death was not caused by the novel coronavirus.
Vietnam has not recorded any Covid-19 deaths so far. Three patients are in critical condition.
The country has confirmed 271 Covid-19 cases to date, of which 50 are active. The active cases include 14 relapses.