A northern Chinese port city on Jan. 9 started mass testing and locked down areas where the highly contagious Omicron variant was reported, prompting residents to stock up on food and supplies. The megacity of Tianjin has advised residents not to leave town for unnecessary reasons and began testing its 14 million residents on Sunday, less than four weeks before the Winter Olympics will open in neighboring Beijing. At a press conference on Jan. 8, Zhang Ying, deputy director of the Tianjin Health Commission, highlighted the city may face a potential outbreak of Omicron as the virus has been circulated in communities, according to official news outlet Xinhua. Tianjin reported a 10-year-old girl and a 29-year-old woman working at an after-school center infected with the Omicron variant on Jan. 8. Late Saturday, health authorities said another 18 people returned with positive results in the subsequent testing of close contacts. Most …