The best test with high accuracy to diagnose COVID 19

Two common laboratory methods used to diagnose viruses such as AIDS, SARS and anew founded Coronavirus (2-SARS-CoV). The first test involved in taking the sample from saliva or nasal discharge to do the qPCR test that finally shows if a person has the virus. The other one involves the antibody test which is taking a month or more to diagnose the patients.

In the middle of January 2019, Chinese researchers identified the genome sequence of the new Coronavirus and made it available worldwide. To diagnose, the throat or nose specimen and in some cases the blood sample of suspicious persons will be sent to the laboratory. Samples are usually taken from people who are having fever, shortness of breath, and cough.

A laboratory method for detecting the new coronavirus uses a method called quantitative polymerase chain reaction using an enzyme called reverse transcriptase. The quantitative chain reaction has the advantage that in addition to detecting the presence of the virus, it can determine the number of viruses by the copy number of the viral genome as well. The reverse transcriptase enzyme copies a part of the single-stranded virus (RNA) genome and then makes a complementary double-stranded (DNA) copy. This genetic content is multiplied by a chain reaction and then identified by fluorescence light and a method called 'real-time' or quantitative, that the amount and type of genetic material of the virus can be found.

In the last two decades, three types of coronavirus have become global or regional: SARS (severe and acute respiratory syndrome), Morse (Middle East Respiratory Syndrome), and a new disease called COVID 19). The causative virus is now called SARS-Corona-2 (SARS-CoV) and is genetically similar to the SARS-CoV virus by 82%. To diagnose the new virus, firstly the test is performed to identify the coronavirus, then the result is confirmed by another test, and if both tests are positive, the third test is used to identify the coronavirus (SARS, Mers, or SARS-Co-19).

In different countries of the world, the defect or inefficiency of Coronavirus diagnosis tests has been reported, while laboratory diagnosis with chain reaction method is very accurate. However, the results of some tests are not conclusive but physicians may be able to diagnose them by looking at clinical signs or other tests, such as a lung scan.

There are also serological tests to measure coronavirus that measure antiviral antibodies in the blood. This type of test shows a previous infection with the coronavirus and is not used to quickly diagnose a possible current disease.

In almost all countries, coronavirus testing is performed in the national laboratory and is not possible in all medical diagnostic laboratories.