If you want to change the health code from yellow code to green code, the recovery method is to do nucleic acid testing. If you have completed the "three-day two-test" after the critical period of possible contact with confirmed cases and asymptomatic infected persons, that is, you have done two nucleic acid tests, and the interval between the two tests is more than 72 hours, and the results are all negative, the system will remove the yellow code and turn it into a green code.
Of course, if your nucleic acid test is positive, the health code will not only become a green code, but also become a red team, because it shows that you are infected with COVID-19 virus. If your nucleic acid test is negative, it means that the risk is relieved, then the health code will be restored from yellow code to green code.