The city’s Center for Disease Control and Prevention said people returning from places where the disease has been found or are under lockdown or social distancing would be quarantined for 14 days and tested four times.

Places under social distancing include the communes of Thuy An, An Sinh, Binh Duong, Nguyen Hue in Dong Trieu Town in the northern province of Quang Ninh and the entire Hai Duong Province, the current Covid-19 epicenter. The latest outbreak began at the end of January after the country had 55 Covid-free days.

As of Wednesday morning Hai Duong has recorded 539 cases, with health authorities saying the outbreak is unpredictable and could last longer.

In HCMC, 36 people have been diagnosed with the disease, 35 of them linked to the outbreak at Tan Son Nhat Airport and the other to Hai Duong.

Both HCMC and Hanoi, which has reported 35 cases, require everyone entering them to make medical declarations.

The port city Hai Phong and nearby provinces that neighbor Hai Duong have imposed a variety of travel restrictions.

Authorities in Quang Ninh, which has 60 cases, have imposed a 14-day quarantine for people returning from Hai Duong and other places that are under lockdown or social distancing. They have to pay their isolation expenses.

Bac Ninh Province, which reported five cases, has imposed similar conditions. Besides, the province, home to foreign tech giants like Samsung and LG, asked to only receive Hai Duong workers showing two negative Covid-19 results using RT-PCR method to return to the locality to work.

Hai Phong has barred the entry of people and goods coming from Hai Duong until March 3 when its social distancing ends.

Locals are prohibited from traveling to Hai Duong except for emergencies. Hai Phong, which has one case, has closed cinemas, coffee shops and restaurants from Tuesday to limit crowds.

Hung Yen Province has banned the entry of people from Cam Giang District and Chi Linh Town in Hai Duong.

Bac Giang Province requires Hai Duong returnees to quarantine and pay for it themselves.

The Year of the Buffalo started on February 12, and Vietnam had a seven-day Tet holiday ending Tuesday. People are returning to work across the country, prompting localities to take drastic measures to prevent further outbreaks.

There have been 719 cases since January 28.