Health codes have a validity period, which is 7 days from the date of health declaration and health code generation to the next 7 days by default. The health code has expired, and you need to declare your health again to get it again. If the health code is invalid due to expiration, click "Update Now" on the QR code to get the health code again.
The static code of health code can only be used for identity confirmation and has no other function. There are two kinds of health codes: dynamic code and static code. Among them, dynamic codes are used frequently, especially during the current epidemic, and you have to show your own dynamic codes every time you go. But static codes also exist, and static codes can only reflect personal identity information.