One bar for nucleic acid generally refers to one bar for the Novel Coronavirus Pneumonia Antigen test, indicating that the test taker is not currently infected with the Novel Coronavirus and does not need to be overly concerned. However, because of the possibility of false negatives in a single test, it is recommended that the test be repeated at least once to be sure. Nucleic acid testing is currently the main clinical tool used to detect novel coronavirus infection in the normal population, and commonly used sampling methods include pharyngeal swabs and nasal swabs. A negative test result means that the patient is not infected with the novel coronavirus, and the patient should not be overly concerned, but should protect himself or herself by avoiding travel to crowded areas and high-risk areas. However, due to a number of factors such as contamination of the sample, a false-negative result may occur in a single test. If the patient is already infected with novel coronavirus but the test result is false negative, going to crowded areas without authorization may cause the virus to spread. Therefore, it is recommended that the patient be tested again at least 24 to 48 hours after the initial test to make sure, and if the second result is still negative, the patient can go out and work as allowed by the local epidemic prevention department. At present, China’s clinical nucleic acid testing technology has basically matured, and the possibility of false negatives is low. However, because the epidemic is not yet fully under control, it is still recommended that patients with negative test results regularly seek medical attention for multiple tests, and if positive test results occur, timely isolation, and cooperate with the prevention and control of the epidemic. Tip: “New coronavirus pneumonia” and “new coronavirus pneumonia” mentioned in this article were renamed to “new coronavirus infection” on December 26, 2022, as announced by the National Health Commission.