Do Thi Thu Ha, director of the Cau Giay District's medical center in Hanoi, said a 20-year-old man from northern Hai Duong Province's Chi Linh Town, where a major coronavirus outbreak revealed itself Thursday morning, tested positive for the novel coronavirus the same night.

The man, who stays on Nguyen Khanh Toan Street on Hanoi's Cau Giay District, was coughing and feverish on Jan. 27 and was taken to the Bach Mai Hospital. His test result returned positive on Jan. 28.

He was in close contact with a 34-year-old woman working for Vietnam Poyun Electronics in Hai Duong, who was confirmed as a community transmission case Thursday morning. The man is now being treated at the National Hospital for Tropical Diseases.

In nearby Bac Ninh, Ngo Thi Xuan, director of the provincial Center for Disease Control, said a 31-year-old man from Lam Thao Commune, Luong Tai District tested positive for the novel coronavirus Thursday afternoon. He is a colleague and had close contact with the woman working for Vietnam Poyun. He's now being treated at a local hospital in Bac Ninh.

The Hai Duong woman had come into close contact with a colleague who tested positive for the virus upon arriving in Japan last week. The colleague was later revealed to be infected by a coronavirus variant originating from the U.K., which is believed to be 70 percent more contagious than ordinary strains.

Both Hanoi and Bac Ninh cases have yet to be officially confirmed by the Ministry of Health.

As Thursday ends, Bac Ninh authorities have tracked down 91 people associated with the new case in the province. They are now either quarantined in centralized camps or at home.

Provincial authorities have locked down Lam Thao Commune with 6,900 residents. The whole Luong Tai District is being considered for lockdown as well if the situation complicates further, said Nguyen Dinh Tam, deputy director of the Bac Ninh Department of Health.

Hanoi authorities have requested those who passed through certain locations with confirmed coronavirus cases: the Van Don Airport and the Muong Thanh Hotel in Quang Ninh, and Chi Linh Town of Hai Duong, to inform themselves to authorities, self-isolate for 14 days and have their samples collected for Covid-19 testing, said Vuong Dinh Hue, the city's Party Secretary.

Following the new cases, Thursday saw 100 community cases recorded nationwide, a record high tally which broke Vietnam's streak of nearly two months without a community transmission. The new outbreaks have now been recorded in Hai Duong, Quang Ninh, Hai Phong, Bac Ninh and Hanoi.