New Crown Positive to Negative and Back to Positive may be associated with false negative nucleic acid tests, secondary infections, and testing errors. 1. False-negative nucleic acid test: It may be the testing method to take samples and other factors, resulting in false-positive or false-negative test results of the phenomenon. 2. Secondary infection: When a patient with new crown pneumonia is cured and discharged from the hospital, and then found to be positive again, the patient may have low immunity, and secondary infection may occur if the patient is not well protected. 3. Detection error: the new coronavirus infection is mainly in the lungs, and the amount of virus in the pharynx is small, this time the test may not be able to collect, and may be detected negative phenomenon. Patients who test positive should report to the local community and actively cooperate with centralized isolation. It is important to live with frequent hand washing and protection. [Note: In this article, “new coronavirus pneumonia” and “new coronavirus pneumonia” were renamed to “new coronavirus infection” on December 26, 2022, as announced by the National Health Commission.