https://www.google.com/search?q=covid+rates+in+China
- Proactive testing and detection. E.g. many places like malls or hospitals require visitors to show a green code on a tracking app in their phone indicating that they are safe.
- Border that is almost closed with extreme quarantine requirements for visitors and quotas for incoming visitors
The Chinese government is able to do the first 2 because of their tight control on people and organizations.
The actual numbers are potentially much higher.