Beijing, Jan 9 (TIWN) North China's Tianjin Municipality, home to 15 million people and also a major gateway and "moat" to Beijing, rolled out massive nucleic acid testing on all its residents on Sunday after it detected 20 Covid-19 infections in one day, including two of the Omicron variant, Global Times reported.

Epidemiologists said it's the first real battle against Omicron on the Chinese mainland as Omicron-infected domestically-transmitted cases were discovered in local communities for the first time.  They also warned of a huge uncertainty and high possibility of a spillover as the source of the outbreak remains unknown, the report said.  Entry checkpoints from Tianjin to Beijing have heightened inspections. Commuters are being asked to contact their employers and communities and sign up a letter of commitment before they are allowed to enter Beijing. Many vehicles and people were persuaded to return. Some residents who returned to Beijing from Tianjin in recent days have been asked to quarantine at home.  The Beijing Centre for Disease Control and Prevention on Sunday asked residents not to visit Tianjin and those in Tianjin not to visit the capital. Commuters between Tianjin and Beijing are encouraged to work from home, the report said.  Anyone in Beijing who have visited Tianjin's Jinnan and Nankai districts since December 23, 2021 will be quarantined at home and tested. Others who have travel history to Tianjin since the same date need to report to their local communities, employers and hotels immediately, the centre said.  Tianjin reported on Sunday two locally transmitted cases with the Omicron variant, which were found among people who volunteered to get tested. Then another 18 cases were found in a follow-up test of high-risk groups.  To ensure the safety of residents and contain Omicron from further spreading, residents of the city are required to stay put and receive a test. The nucleic acid testing on all residents started on 7 a.m. Sunday morning and is expected to complete within 24 hours, according to a notice from the city's anti-epidemic command centre.  As of Saturday night, Tianjin has quarantined 75,680 people. Among 70 environment tests, 14 of were positive and two were detected in elevators of residential buildings.  The health code of people who won't receive the test within 24 hours will be turned to orange. Residents who have been vaccinated for less than 48 hours will not participate in the test, the command centre said.  The anti-epidemic command center said at an urgent meeting, participated by the city Party chief Li Hongzhong and mayor Liao Guoxun, on Saturday night that the massive testing is a concrete measure to fulfill the responsibility of Tianjin to be a "moat" of Beijing and contain the epidemic at the fastest speed and the lowest cost.