A negative self-test for Neocoronavirus antigen is not always accurate and may be a false negative. Neocoronavirus antigen testing refers to the detection of the antigen of the virus with antibodies that allow the virus to show up to determine if a neocoronavirus infection has occurred. There are two types of negative neocoronavirus antigen tests, a true negative and a false negative. A negative antigen self-test is not necessarily accurate. A false negative antigen test is a missed test, where the tester carries the pathogen and the antigen test result should be positive, but the result appears negative. False-negative results can be caused by irregular sampling, where samples taken from the upper respiratory tract, such as nasopharynx and oropharynx, do not always pick up pathogens, or the samples may contain a small number of pathogens. Antigen testing is generally used during the acute phase of infection, i.e., within 7 days of the onset of symptoms in the suspected population. Both antigen-positive and negative results in suspected populations should be followed by further nucleic acid testing. Positive results can be used for early triage and rapid management of suspected populations, but cannot be used as the basis for definitive diagnosis of new coronavirus infections. Compared with nucleic acid testing, antigen testing is more widely available and relatively inexpensive. However, compared to nucleic acid testing, which is the “gold standard”, its accuracy may be lower and the probability of missing a test is higher.