Big data shows the intersection of time and space, but there is no code change.

It is possible that in the process of QR code recognition, the surrounding network is weak and the transmission path is disturbed.

How to manage the "time companion" varies from place to place. Rolling reminder, citizens should always pay attention to the status of health code after receiving SMS reminder from CDC. If the health code is temporarily green, citizens should immediately report to their communities (villages) and units and do a good job in personal health monitoring. It is suggested that nucleic acid detection should be carried out as soon as possible under personal protection conditions.