A newly detected coronavirus outbreak in Vietnam, which has infected 276 people and spread to 10 provinces and cities, was caused by the more contagious British variant of the coronavirus.
Six days after the virus re-emerged in the northern province of Hai Duong, the cluster there is under control, health minister Nguyen Thanh Long said.
Containing the virus in the capital, Hanoi - where 20 new cases have been detected - would take longer, he added.
"Gene sequencing showed that 12 of 276 newly detected patients are positive with the UK variant, although the source of this outbreak remains unknown," Long told a cabinet meeting.
"We need to scrupulously follow mask-wearing regulations."
Thanks to targeted mass testing and strict quarantining, Vietnam has kept its virus tally to a low 1851 cases and 35 deaths, winning plaudits worldwide for one of the most successful national responses to the pandemic.
"Hanoi has to increases measures to contain the virus. The health ministry will support the city to upgrade testing capacity to 40,000 tests per day," Long said.
Hanoi has taken 15,000 samples since the latest outbreak and currently has capacity to conduct 5,000 tests a day, an official from Hanoi's health department said on Monday.
Vietnam approved the AstraZeneca vaccine on Saturday after Prime Minister Nguyen Xuan Phuc said the country must begin inoculation in the first quarter of 2021.
The government had previously said it was in talks to procure 30 million doses of the vaccine.
State media reported the first batch of 50,000 doses would arrive by March, with the rest delivered by June.
Vietnam reported one new coronavirus case on Tuesday.