China sees its largest outbreak of the coronavirus Delta strain, putting the zero-case policy to the test. Restrictions have been imposed on a university town in the northeastern part of the country.

Over 10,000 students were quarantined following the closure of two big dorms in the university town of Zhuanghe, which is administered by the city of Dalian in the northeastern Chinese coastal province of Liaoning.

Since November 4, health officials have reported more than 230 Covid-19 instances in Dalian, a metropolis of 7.45 million people. Authorities increased restrictions, including road closures, and started a citywide mass testing effort to adhere to their zero-case plan.

The more contagious Delta variant outbreak has been linked to enterprises that store and handle frozen food. At the same time, another cluster of cases was detected on a student campus, Chinese media reported.

Wu Liangyou, deputy director of the National Health Commission's disease control and prevention section, said Sunday that the Dalian epidemic was "at a stalemate" and that the virus had not moved to other locations.

China was able to control the spread of Covid-19 to a great extent in the early months of 2020, owing to a combination of intensive lockdowns, contact tracing, and mass testing. Since then, authorities have been battling viral hotspots that have appeared in various parts of the country.

Reuters calculated that 1,308 locally transmitted symptomatic cases were reported in China between October 17 and November 14, compared to 1,280 similar cases during the summer's Delta wave.