Why did you suddenly receive a text message four days after the nucleic acid results came out?

Abnormal nucleic acid results are usually prompted by short messages. After the nucleic acid test results come out, they will inform me of the abnormal results as soon as possible. I, in general, will notify them by SMS, but it is not excluded that some areas will notify them by telephone. However, in any case, it is necessary to go to the designated place for isolation at the first time after receiving the notice, wait for the staff to be transported to the designated hospital for isolation, and return to normal until the re-examination result is negative and the risk of infection is ruled out.