If you need to leave Hebei in the near future, or go to other provinces after 14 days, you still need to do nucleic acid testing again, subject to the latest nucleic acid results.
Broadly speaking, the validity period of nucleic acid test report is 14 days, and the incubation period of novel coronavirus is about 14 days. A negative nucleic acid test usually proves that the body is not infected with novel coronavirus. The detection of nucleic acid is limited by its detection conditions, and there will be a certain false negative probability. Therefore, repeated detection can improve the probability of positive and reduce the risk of false negative.