As the 2022 Beijing Olympics approach, China has imposed a strict lockdown affecting about 13 million people. 

Authorities imposed the lockdown on the Chinese city of Xi’an as 63 new cases of COVID-19 were reported on Wednesday, CNN reports. The lockdown measures prevent people from being able to leave their homes outside of emergency situations. The city’s number of new cases passed 200 over the course of the past week, The Associated Press reports. 

The strict lockdown came as China is set to host the Winter Olympics in Beijing beginning on Feb. 4 and amid concerns over the Omicron variant of COVID-19, although there reportedly haven’t yet been any cases of the Omicron variant reported in Xi’an. China has pursued a policy of striving for “zero COVID” during the pandemic; in November, over 30,000 people were locked inside Shanghai Disneyland for testing after a single COVID-19 case was reported. But according to CNN, this was just the fourth time during the pandemic that an entire Chinese city was put into what’s known as a “controlled area” lockdown, the second strictest kind of lockdown. 

China previously banned foreign spectators from the Beijing Olympics, and according to The New York Times, it’s taking “elaborate precautions” to prevent the spread of COVID-19, including having participants stay inside a “closed-loop” bubble. Still, the Beijing Winter Games organizing committee secretary general said Thursday, per the Times, “A certain number of positive cases will become a high probability event.”