Vietnam reported nine more new Covid-19 infections early today as the country’s first outbreak for nearly two months spread to Hanoi, the capital, where the ruling Communist party is currently holding its key five-yearly congress.

The new cases, including one in Hanoi and eight in nearby Haiphong city and Hai Duong, Quang Ninh, and Bac Ninh provinces, brought the total number of cases in the outbreak that began yesterday to 93, the Ministry of Health said.

One of the first two cases recorded yesterday was exposed to an individual who had tested positive in Japan for the more contagious UK variant. The ministry said it was still analyzing gene sequences to determine if the new patients had contracted the new variant.

The total number of cases recorded since the coronavirus was first detected in Vietnam a year ago stands at 1,651, including imported cases, with 35 deaths. The ministry is scheduled to provide an update on the outbreak at 1100 GMT.

The ministry said the case in Hanoi is linked to an airport worker in Quang Ninh province who tested positive yesterday along with 83 others, the first locally transmitted cases in the country for 55 days and the biggest single-day outbreak so far.

Early today authorities imposed a lockdown at a 27-floor apartment building in a central Hanoi district where the person who tested positive lives, state media reported. All residents in the block, home to hundreds of people, were asked to remain in their apartments until further notice.

“Hanoi faces a high risk of detecting new community transmissions,” local media outlet VnExpress quoted Hanoi health department deputy director Hoang Duc Hanh as saying. “Without good management, the capital could become a Covid-19 hotspot.”

Prime Minister Nguyen Xuan Phuc urged calm and promised swift action at an urgently called meeting on the sidelines of the congress yesterday, when the wearing of face masks at the event was made mandatory. Against a backdrop of a buoyant economy, bolstered by keeping coronavirus cases in check so far, the congress will select Vietnam’s leadership and shape policy for the next five years and beyond.

Congress delegates were tested for the virus at their hotels yesterday, state media reported. Anti-virus measures were also stepped up at the congress venue today: all support staff and media in attendance underwent another round of testing — the third for those involved since the run-up to the event began. The health ministry previously said it conducted 10,000 tests in association with the congress, all of which were negative.

At an urgent meeting held yesterday night, Hanoi authorities said they were ramping up tracking and testing capabilities, adding that the city can conduct 10,000 tests a day. State television quoted the coronavirus taskforce chief as saying preparations should be made for a scenario of up to 30,000 Covid-19 cases.

The health ministry has proposed halting international flights and banning large gatherings ahead of the Lunar New year holiday season, just two weeks away. The government late yesterday said it will build three field hospitals in Hai Duong province, without giving their sizes.

State media today reported a deputy police chief of Hanoi said the city has no shortage of policemen to help handle the outbreak, despite the ongoing Party congress.