Is a positive nucleic acid test a confirmed diagnosis? Can a throat swab be positive for the common cold?

Coronavirus is composed of protein and ribonucleic acid, and ribonucleic acid is responsible for the reproduction of the virus, so the nucleic acid test is a method to directly detect the presence of the virus at the moment, but is a positive result from this test method sufficient to locate a confirmed diagnosis?

①. Is a positive nucleic acid test a confirmed diagnosis?

No, not yet. According to the "Novel Coronavirus Pneumonia Treatment Protocol (Trial Version 7)", the diagnostic criteria for a confirmed case of Novel Coronavirus pneumonia, a positive nucleic acid test needs to be combined with clinical manifestations and other test results such as lung CT to determine whether a positive test is a confirmed case of Novel Coronavirus pneumonia.

If a subject has a positive pharyngeal swab for nucleic acid but does not have clinical symptoms, such as fever and dyspnea, and there is no obvious manifestation of viral infection on lung CT, then he or she will be called an asymptomatic infected person. Asymptomatic infected persons also need to be placed under intensive medical observation, and active prevention and control policies such as isolation will be adopted to prevent them from becoming a source of infection, and once an asymptomatic infected person develops clinical manifestations, he or she will be promptly revised to a confirmed case .

② Can the first positive nucleic acid test confirm the diagnosis?

No. Positive nucleic acid test can confirm the diagnosis of the virus infection, in the case of novel coronavirus pneumonia, for example, the positive case is determined by the same specimen of the new coronavirus 2 targets (open reading frame 1A/B, nuclear capsid protein) specific real-time fluorescence RT-PCR test results are positive, if only single target nucleic acid test positive, the patient can not be identified as a viral infection, but also can not exclude being infected, so In addition, a negative nucleic acid result cannot rule out infection by the novel coronavirus, and factors that may produce a false negative need to be excluded.

③. How many times does a positive nucleic acid test confirm the diagnosis?

Two or more times. Novel coronavirus nucleic acid testing is the most important tool for diagnosing novel coronavirus infection. Usually, nucleic acid testing can be performed on nasopharyngeal swabs or pharyngeal swabs, and sometimes sputum or alveolar lavage fluid specimens are also taken from patients for nucleic acid testing.

No matter which specimen is positive, it is accurate and can be used as a basis for the initial diagnosis of novel coronavirus infection.

In order to ensure the rigor of the medical results, to determine the infected generally need to carry out two or more throat swab test, two positive throat swabs to be considered infected, two sampling time interval of 24 hours, and two negative nucleic acid test throat swabs is also an indicator of discharge.

④. Will the pharyngeal swab of common cold be positive?

Yes, it will be positive. Because pharyngeal swab test is a test method to detect the type of virus infected in the patient's body by collecting the secretion from the patient's throat, if the pharyngeal swab is positive, it means there is virus in the body. However, the laboratory doctor will further check the type of virus that the patient is infected with and determine the type of disease that the patient is suffering from by the type of virus, but if it is a common cold, it will not be diagnosed as a new coronavirus.