It’s not going quite as well as they’d hoped.

Officials in Beijing on Monday said they had discovered “dozens” of cases of coronavirus in the so-called Olympic bubble, a closed-loop, fenced-off area that’s meant to halt the spread of the virus. Foreign and local athletes, along with Olympic officials, journalists, and support workers, are not permitted to leave the bubble as China maintains its zero COVID policy. New arrivals are required to take a PCR COVID test when they arrive.

Olympic officials say they found 37 cases at the airport or within the bubble on Sunday, following the discovery of 34 cases on Saturday. To date, they’ve discovered 176 total cases (46 within the bubble). In the past week, over 6,000 bubble-residents have arrived, with more to come.

People who test positive are given a second test. If that confirms the diagnosis, they’re sent to quarantine zones or COVID-designated hospitals. Athletes who test positive are not allowed to compete until they’ve finished a seven-day isolation, followed by two negative tests.

China’s pursuit of a zero COVID goal has been controversial.  In one of the country’s northwestern cities, a man with chest pains was unable to get help at his local hospital because he lived in a medium-risk district. (He died of a heart attack.) Pregnant women have also lost their children because of strict rules. And some areas have seen lockdowns, with have sometimes devastating consequences on people’s mental health and well-being.