Antibodies are proteins that help our immune system identify and eliminate threats to our body.
What is Antibody Test?
It helps protect against the same virus in the future if immunity is provided. “Antibody tests”, which are frequently mentioned these days when we are experiencing a Covid-19 pandemic, are a test for detecting these protein structures in the blood in order to understand whether the person has encountered the SARS-CoV-2 virus and has responded. “Why is the antibody test done?” answer to the question; It is to determine whether the person has had the disease whose antibody is sought in his blood.
What are IgM- IgG Antibody Tests?
IgM (early stage antibody) antibody shows that the person has recently encountered the Covid-19 virus. These antibodies are not protective. Studies have shown that IgM antibody can usually be detected from the 7th day and disappeared from the 21st day.
IgG (late response antibody) antibody occurs in the late period of Covid-19 infection. It indicates that the immune system responds adequately to the virus and creates protective antibodies. Studies show that IgG antibody production starts from the 14th day of infection and continues to remain in the blood, providing long-term immunity.
How Long Do IgG Antibodies Against Covid-19 Protect Us?
We do not know exactly how long the IgG-type protective antibodies formed in those who have had Covid-19 infection will remain in our body and how long they will protect us. Studies show that the amount of Covid-19 IgG type antibody in the blood decreases over time. The duration of protection of antibodies against infections varies. But the antibodies formed in the influenza virus, which is a seasonal flu agent, will only be enough to protect you during that epidemic period. For this reason, we recommend that people with chronic diseases or those over 65 years of age should repeat the influenza vaccine every year.
How is the Antibody Test Performed?
Like other antibody tests, the antibody test for Covid-19 can be performed in the reference laboratory. In our bees, ELISA method is used by using patient blood samples.
Both IgM and IgG type antibodies in the blood are detected with 99.8% specificity (no false positives) rate by ELISA method. Although blood antibody test results vary according to the number of tests performed daily in our laboratory, they are usually given on the day the sample is taken.
Is Antibody Test Alone Sufficient for Diagnosis?
Covid-19 antibody tests should not be used alone for diagnosis.
- Antigen tests are tests that identify whether a person is sick, that is, the presence of an acute infection.
- The gold standard in the diagnosis of Covid-19 is the Covid PCR test.
- Antibody tests, on the other hand, are intended to define whether the person has had the infection before and whether he has become immune to the virus.
- If the patient's Covid IgM antibody is positive in the presence of the appropriate clinical picture, in the active period of the infection (5th-10th.
- It shows that a person who is negative for Covid-19 Ig M antibody and positive for Ig G antibody has recovered from the infection and developed immunity.
Interpretation of Covid-19 Ig G Antibody Results
- Negative Test (<0.9 negative): Test result 0, If it is less than 9, it means that the patient
has been infected/infected with the Covid-19 virus but has not developed IgG antibodies.
- Positive Test (≥0.9 positive): If the test result is 0.9 and above,
Antibody Tests Who Should It Be Done?
- To evaluate whether immunity has developed in those who have had Covid-19 disease,
- To detect those who have antibodies since the majority of those who have the disease without clinical signs (asymptomatic) ,
- For the purpose of screening the employees of factories, banks, schools, chain brands preparing for normal working order,
- Antibody tests are carried out to determine what percentage of the society is immune by screening a certain number of individuals or groups in the society. In similar studies conducted in the world, it has been found that herd immunity is between 5-9%. is known to be in
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