China is working to create a digital health certificate system to facilitate global travel amid the coronavirus pandemic. Chinese State Councilor and Foreign Minister Wang Yi announced it last Sunday at a virtual news conference on the sidelines of the National People's Congress. Chinese citizens can now access the system via a WeChat mini program. Wang said the digital health certificate system would enable countries to mutually verify travelers' coronavirus test results and vaccination records. What difficulties would have to be overcome to implement an international health certificate?