A positive and a negative nucleic acid test is not normal. If there is a positive result one day after a negative result in the nucleic acid test, it is abnormal, indicating that the person being tested may be infected. Since there is a certain incubation period after being infected with the New Coronavirus, not all infected persons can have a positive result in a single nucleic acid test, and they should be retested in a timely manner. However, it is not normal to have a positive result one day and a negative result the next; there may have been false positives during the previous day’s testing, and similar results can occur due to vaccination, environmental positives, and other factors, which also require timely retesting, expert verification, and other procedures.