The resurgence of positivity after infection with the new coronavirus may be due to experimental errors or reinfection with the virus. 1. Experimental error: In the clinic, there have been cases in which the test results were wrong due to the poor quality of specimens, inappropriate timing of collection, improper preservation and other factors, which may result in false-negative results in the first test, and then re-positive results in the second test. 2. Re-infection of virus: After being cured, patients with novel coronavirus pneumonia usually become resistant to this type of virus. However, if the patient’s immunity is low, it may prevent the formation of antibodies, leading to the proliferation of the virus after the patient is discharged from the hospital, and the result will be positive again. Or the patient may be re-infected with the same or a different strain of the virus after being cured, resulting in another positive result. Doctors need to take into account the patient’s epidemiologic history, symptoms, other laboratory tests, chest CT results, and two or more negative nucleic acid tests at twenty-four-hour intervals before the patient is discharged from the hospital to determine whether the patient has reached clinical cure. If the patient is not feeling well after discharge from the hospital, he/she should consult a doctor for review and treatment. Tips] In this article, “new coronary pneumonia, new coronary virus pneumonia” has been renamed to “new coronary virus infection” on December 26, 2022, as announced by the National Health Commission.