Vietnam confirmed 31 coronavirus infections, more than half in the epicenter Da Nang, and one virus-related death on Sunday.
All the new cases were traced back to Da Nang, a touristy city on the central coast that began emerging as an outbreak hotbed late last month, the National Steering Committee for COVID-19 Prevention and Control said.
Nineteen of the patients were recorded in the coastal city, eight in neighboring Quang Nam Province, two in Quang Tri Province, one in Hanoi, and one in Bac Giang Province.
A 55-year-old COVID-19 patient was pronounced dead on Sunday, taking the death toll to eleven.
She had a history of high blood pressure.
Vietnam has documented 841 coronavirus cases as of Sunday night, of which 317 were imported and 395 have beaten the virus.
The dead, except the latest fatality, all had severe underlying conditions.
The number of domestic infections linked to Da Nang has hit 384 since July 25, when the touristy city logged Vietnam's first locally-transmitted case after 99 days.
The pathogen has spread to 14 other provinces and cities in Vietnam since.
A total of 178,695 people who were in close contact with detected patients or entered the Southeast Asian country from outbreak-stricken regions are being quarantined when this story goes to press.
Over 19.8 million people have gone down with COVID-19 around the world, with above 12.7 million having recovered from the disease, according to statistics.
The virus has killed more than 730,000 people globally.