Diagnostic tests play a critical role in controlling the COVID-19 outbreak that affects the world.
It is also of great importance for people diagnosed with coronavirus to take the necessary precautions in isolation from the society after the test. PCR, ELISA IgG and IgM antibody tests, rapid tests and PCR home kits are used for diagnosis in people with suspected coronavirus. It is very important to know what these tests mean and what results they give with which indicators in the body in order to take the right steps in combating the disease. In addition, practical PCR test kits, which can be applied by the person at home, provide great convenience to those who are afraid to go to the hospital or who do not have the opportunity to go to the hospital, and contribute to preventing the spread of the virus with the continuation of social isolation.
From the Department of Infectious Diseases and Clinical Microbiology, Memorial Şişli Hospital Uz. Dr. M. Servet Alan gave information about PCR and antibody tests required for all stages of the Covid-19 virus.
PCR test is done by taking a swab from the throat and nose.
The PCR test applied in the diagnosis of COVID-19 is a safe test that allows people with COVID-19 disease to be identified at the earliest stage, even if there are no symptoms. Early diagnosis of the disease also helps early initiation of the treatment, isolation and prevention process. The method called Polymerase Chain Reaction (PCR) detects the genetic material (RNA) of the virus. In PCR tests, which are a molecular test, a swab is taken from the throat and nose with the help of a cotton swab. This example, when properly taken and studied, gives extremely accurate results.
PCR testing can also be performed at home
It is very important for people with suspected illness to be isolated at home, to prevent the spread of coronavirus and to control the disease. For this reason, there has been a need for people who do not want to leave their home and cannot go to the hospital to have a PCR test by taking a swab sample at home or in the environment they are in. PCR Test kits at home allow the person to take samples from his throat and nose, send it to the laboratory in a box, and learn the results online. These tests, which support the isolation process at home and thus prevent the increase in the number of people to be infected, are also known as rapid diagnosis. Home PCR tests differ from rapid diagnostic kits with their reliability. The most important point to be considered here is that the samples are taken correctly and hygienically and in accordance with the precautions to prevent contamination to others. If possible, no other people should be around the person taking the sample. In order for the tests to give correct results, samples must be taken by following the specified steps.
In addition to people over the age of 65, who do not want to leave their home, who cannot go to the hospital, who have limited mobility and who are in the risk group due to chronic illnesses and therefore the isolation process should not be impaired; PCR test application at home is also an important option for people who have to be in closed and crowded areas, who frequently travel abroad or intercity and want to visit their relatives. It is also possible to take samples for PCR, antibody or other medical tests at home through home care services. No test meets this need in a situation where a doctor's examination is required.
Possibility of false negative results in rapid antigen tests
Antigen tests detect some proteins of the COVID-19 virus. The results of fluid samples taken from the nose and / or throat with a swab can also be obtained in a very short time. These tests are cheaper and faster. Since it is much cheaper and faster than PCR tests, it can be preferred in terms of testing a large number of people. However, these tests, currently unsuitable for widespread use, may yield 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. In this case, control by PCR test is required.
Those who wonder if they have had COVID-19 before ...
Due to the COVID-19 pandemic, people with a simple cold also worry about the coronavirus, and many people wonder if they have had the disease before. In this case, antibody tests that determine whether the person has encountered COVID-19 before becomes important. IgM and IgG antibody tests are tests that are studied by taking blood from the vascular access, and can show the person's coronavirus with or without symptoms and immune status. While IgM identifies people who have had the disease or who have recently had the disease, IgG appears about two weeks after the onset of the disease and can be detected longer than IgM. Treatment with plasma taken from people who have had COVID-19 and developed antibodies in patients with severe COVID-19 symptoms gives successful results.
If the antibody test is positive ...
Antibody tests are also used to determine the rate of exposure to the COVID-19 virus in the community, in other words, to determine how much of the society has had this infection. In the first days of encountering the virus, the immune response has just begun and antibody may not be detected. After the antibody is formed, the presence of the antibody continues to be detected for a while, even if the infection ends. Therefore, antibody tests alone are not used for the diagnosis of active COVID-19 infection. It is extremely reliable when antibody tests are found to be positive. However, in some people, even though they encounter the virus, antibodies do not form or the antibodies formed may disappear after a while. Positive for COVID-19 antibody; It does not indicate that there is complete immunity against coronavirus, that the disease is protected or that the virus will not be transmitted to others. People who have had coronavirus infection should also follow the same social distance, hygiene and mask rules.
You can have your PCR and Antibody tests done together.
The sensitivity and accuracy of antibody tests performed with ELISA and similar methods are much higher than rapid antibody tests with low reliability. The use of sensitive and highly specific methods such as ELISA IgM and IgG together with PCR contributes to the chance of accurate diagnosis and gives an idea about the disease stage.