The difference between being negative and positive for novel coronavirus is the difference between being infected and not being infected. If the nucleic acid of novel coronavirus is negative, it proves that there is no infection with the virus, and if the nucleic acid is positive, it means that there is a viral infection. However, a positive test does not necessarily mean that there are any clinical symptoms, such as patients who are now asymptomatically infected but have a highly suspicious history of suspected exposure. If the novel coronavirus test is negative, it will be retested 24 hours later because the nucleic acid may not have been detected in the early stages or there may have been a test error. Infection can only be ruled out if the test is still negative after an interval of 24 hours, so the difference between negative and positive for novel coronavirus lies in the difference between being infected and not being infected.