BEIJING (Reuters) – Central Chinese cities including Yuzhou and Zhengzhou imposed varying degrees of travel curbs after sporadic COVID-19 cases, in line with a national strategy that has taken on extra urgency as the Winter Olympics and Lunar New Year holiday approach. The city of Yuzhou in the central province of Henan has ordered its 1 million residents not to leave town since Jan. 2, although the caseload for the city and the entire province remained tiny. Henan reported four domestically transmitted cases and 18 local asymptomatic infections for Tuesday. China’s strategy demands that offic…