The health code reflects whether there are any cases in the province where you recently arrived, your physical condition, etc. Information is time-sensitive, last year's and can't cash out your current situation, so it can't be used.
The application of health code covers community management, enterprises' resumption of work, transportation, school opening, drug purchase registration, supermarkets and shopping malls, etc., which can help communities, enterprises and schools to do key work such as epidemic prevention management and epidemic control.