"Patient 137" is a 36-year-old man from the central province of Nghe An who visited Germany and returned to Hanoi March 15. He was confirmed positive for the novel coronavirus on March 25 and treated at the National Hospital of Tropical Diseases in Hanoi. The man was discharged on April 7 after treatment, following which he continued to be quarantined for another 14 days. He left the hospital on April 22 after testing negative for six times. Before leaving the hospital, he had his samples taken for the seventh time.

A day later, the test result was confirmed positive by the Central Institute of Hygiene and Epidemiology, but by then he had returned to his home in Nghe An, around 330 km south of Hanoi.

On Thursday night, he was taken back to the National Hospital of Tropical Diseases and had his samples tested gain. The result has not yet been announced.

Duong Dinh Chinh, Director of the Nghe An’s Health Department, said local authorities had disinfected the patient’s home and neighborhood after receiving information from the hospital that he had tested Covid-19 positive again.

Authorities said that after leaving the hospital, he took a taxi home and along the way he stopped in Ninh Binh Province to change money. He went into a restaurant in Tinh Gia District, Thanh Hoa Province. Before returning to his house in Yen Thanh District on the night of April 22, he informed his relatives to prepare some necessities for him and leave the key at the gate so that he could let himself in. All his relatives left home before he arrived.

"The patient said he had been home for one day and had not been in contact with anyone yet. However, his wife, children and uncle have been asked to isolate themselves at home. Health officials are continuing to verify the epidemiology of the patient carefully," said Chinh.

Earlier, "Patient 188," a 44-year-old woman from the capital city’s Chuong My District, had tested positive for the Covid-19 virus on April 18, two days after her discharge. However, she tested negative again and is still under treatment and observation in Hanoi.

The other relapse case is "Patient 22," a 66-year-old British man who flew from the U.K. to Vietnam on March 2.

He was confirmed Covid-19 positive on March 8 and treated at the Da Nang Hospital in the central city. He was discharged March 23 after testing negative three times. After finishing a post discharge two-week quarantine at a local hotel, he flew from Da Nang to Saigon for a flight back to the U.K. on April 10. Another sample was taken when he left, and it tested positive for the novel coronavirus the next day. He had already left Vietnam by then, but has since tested negative again, U.K. authorities said.

Cases of Covid-19 patients testing positive again after recovery are not uncommon. South Korea has reported relapses in more than 200 people.

Vietnam has recorded no new Covid-19 infection in the last eight days. It has discharged 225 patients in a total of 268 infections.

The Covid-19 pandemic has spread to 210 countries and territories, with more than 191,000 deaths reported so far.