This test is used for the in-vitro qualitative determination, in just 15 minutes of the antigens against the new SARS-CoV-2 strain that first appeared in the Chinese city of Wuhan in November 2019 and was declared a pandemic in March 2020 by World Health Organization (WHO). The virus cause COVID-19 infection which results in a variety of complications, ranging from a simple cold to severe acute respiratory syndrome type 2 (SARS). Sample collection takes place using a swab to collect nasopharyngeal/ oral pharyngeal smear, done by qualified health professionals of our laboratory.
The test principle is based on immunochromatographic method, which the SARS-CoV-2 antigen is identified in the sample, commonly the nucleocapsid protein of the virus. The test consists of a plastic cassette, with a sample insertion point and a buffer solution. The cassette consists of a control test to confirm the proper function of the cassette (C-line). The nitrocellulose membrane of the cassette is sensitised with a monoclonal antibody which binds to the antigen of SARS-Cov-2 in the T-line test detection line, while another conjugated monoclonal antibody sensitizes the C-line quality control line. The sample is place on the cassette and via the capillary effect, the liquid rises to the top of the cassette. When nasopharyngeal secretions come in contact with the strip, the solubilised conjugate migrates with the sample via passive diffusion and the conjugate antibody along with the sample, come in contact with the anti-SARS antibody absorbed on the nitrocellulose membrane. If the sample contains SARS-CoV-2, the SARS-CoV complex remains bound to the anti- SARS-CoV-2 antibody, immobilised on the nitrocellulose membrane, producing a positive result. The differentiation of this test in comparison with other rapid antigen detection tests, is that when using the immunochromatography analyser the ratio of T-line and C-line signals can be calculated, thus giving a quantitative form of SARS antigen concentration. -CoV-2 present in the sample.
In a clinical study conducted with hundreds of samples, the sensitivity, specificity, and reliability of the test have been confirmed to be close to 98.55%, 100% and 99.51% respectively. Although the rapid detection test offered is highly accurate in the early days of infection, the molecular test (RT-PCR) is considered the most reliable test as it detects low amounts of the virus over a longer period of time.
It is important to emphasise that although this test has high sensitivity and specificity, it is advised to verify the positive results with the molecular test.
The fast-producing time of the results as well as the professionalism of the health professionals of our laboratory, where all the precautionary measures are taken for both themselves and possible cases make this test ideal for mass checks in places where there is increased assembly so that positive people can detect easily and limit the spread of the virus immediately.
Our laboratory along with the specially trained staff, that offers both the molecular RT-PCR test and the rapid antigen detection test and has been engaged in the battle for early detection of cases to stop the COVID-19 pandemic.