People flock to Hanoi on February 16, 2021, the last day of the seven-day Tet break. (Photo: VnExpress)

The province, which has a population of more than two million, began a 15-day social distancing campaign on Tuesday. It has reported 557 cases so far, with all its 12 towns and districts having patients.

Earlier Hanoi authorities had only required those arriving from Hai Duong to make medical declarations and quarantine themselves at home, and sent only people arriving from the province’s biggest hotspot Cam Giang District to quarantine and tested them for Covid.

Khong Minh Tuan, deputy director of the Hanoi Center for Disease Control, said the outbreak in the capital is "basically under control."

He said the biggest risk for the city now is the influx of people from Hai Duong after Tet since a large number of workers from the province work in Hanoi.

Hanoi has recorded 36 cases so far.

HCMC and some northern localities have also mandated a 14-day quarantine or even barred entry for people coming from Hai Duong.