Release Date: 08 12 2020
Writer: SPECIALIST M.D. Nevil Aykın
COVID-19 DIAGNOSTIC TESTS
Antigen and antibody tests are used in the diagnosis of Covid-19. Antigen tests identify whether the person is sick, in other words, the presence of an acute infection.Antibody tests check your blood by looking for antibodies, which may tell you if you had a past infection with the virus that causes COVID-19. The antibody test isn't checking for the virus itself. Instead, it looks to see whether your immune system -- your body’s defense against illness -- has responded to the infection. A wide variety of test kits are used for diagnosis and screening purposes on the market, and many of them do not have the approvals issued by National or International authorities. Which test can be used for diagnosis, which one can be used for screening, and which test to be performed at which stage of the disease in order to make a correct diagnosis requires a health professional approach.
Our COVID-19 diagnostic tests are carried out in our laboratory authorized by the Ministry of Health with sensitive methods using test kits with National and International conformity certificates and precise measurement methods.
The PCR test is a safe antigen test that allows people with COVID-19 disease to be identified at the earliest stage, even if there are not any symptoms.
COVID-19 test detects genetic material of the virus using a lab technique called polymerase chain reaction (PCR). A fluid sample is collected by inserting a long nasal swab (nasopharyngeal swab) into your nostril and taking fluid from the back of your nose or by using a shorter nasal swab (mid-turbinate swab) to get a sample.
This test is carried out in the PCR laboratory in our hospital authorized by the Ministry of Health.
The PCR test usually results in 3 to 4 hours. However, this period may be extended up to 1 day, depending on the laboratory conditions, intensity or the test may need to be repeated.
The PCR test is the most reliable diagnostic test known today for COVID-19.
Rapid Antigen Tests For Covid:
One type of rapid diagnostic test (RDT) detects the presence of viral proteins (antigens) expressed by the COVID-19 virus in a sample from the respiratory tract of a person. (card test) You can get results in 15 minutes. These tests are cheaper and faster, but less sensitive than PCR tests and may give a 'false negative' result. False negativity is when the test result is found to be negative even though the person is infected with the virus.
For this reason, it is recommended that people with symptoms of coronavirus be confirmed with the PCR test, even if the rapid test results are negative.
IgM antibodies indicate an early stage response of the immune system, with symptoms appearing within the first two weeks after infection. It becomes positive from the 7th day.
IgG type antibodies are positive from the 11th-14th day and show the body's immunity against the virus that causes COVID-19. This positivity can usually be detected for a few months. The persistence of Covid-19 IgG antibodies allows people who have been infected in the past, recovered and possibly immunized, to be identified.
Covid -19 virus-specific IgM and IgG antibodies are measured in the blood sample with autoanalysers and reference methods in our laboratory. The test is concluded on the same day.
Our antibody test kits and analyzer are FDA and Ministry of Health approved.
The sensitivity and accuracy of antibody tests performed with Elisa and similar methods are higher than rapid antibody tests taken from the finger.(card test, rapid antibody test etc. )
Rapid Antibody Tests:
With a blood sample taken from a finger or a vein, a method called card test is performed manually, without the need for a device, and results in Positive / Negative within 10-15 minutes.
It shows whether protective antibodies (IgM and IgG) have appeared in the blood after the disease has started. Whether the antibody tests give correct results is evaluated according to the sensitivity and specificity rates. Test kits, especially from China, are not recommended; it is important that, which kit used when performing an antibody test.
These tests are also not recommended by the Ministry of Health.