In the face of today’s COVID-19 epidemic, a great deal of information can be found on research on this virus online. To facilitate this, we provide you with systematic and specific information about the COVID-19 (Serological COGID-19 IgG) antibody test. You will learn the purpose of this test, what a negative result means and why the results may vary from lab to lab.
What is the purpose of testing IgG antibodies in COVID-19?
Serological tests for COVID-19 IgG antibodies are used to detect antibodies to the IgG class of the virus (SARS-CoV-2). A semi-accurate quantitative test detects IgG antibodies against the Sars-CoV-2 S1RBD barbed protein.
The COVID-19 antibody test is used as a tool to diagnose coronary heart disease and to determine if a person is already ill. In short, this test may show COVID-19 infection present or past. It is important to note that this test is not suitable for early diagnosis, as the human body simply will not yet be able to produce the antibodies tested in this serological test.
Corona virus vaccines have been introduced in Lithuania and around the world to stimulate the body to produce protective antibodies that block the entry of the SARS-CoV-2 virus into cells. To make sure your body has enough antibodies after the vaccine, you may want to test COVID-19 IgG antibodies and make sure you are immune to this virus. Thus, the serological test of COVID-19 can play an important role in assessing and responding to the need for a vaccine. COVID-19 IgG testing is necessary if you decide to be a plasma donor in patients with severe corona infection. After recovery from coronary heart disease, donors are best suited for plasma donation during an asymptomatic period, i.e. 14 days after the start of recovery. It is advisable to offer a donation for up to 5-6 months, as during this period it is likely that plasma antibody levels will suffice.
The result (answer) of my research is positive. What it means?
A positive IgG antibody test for COVID-19 means that the body has produced COVID-19 IgG antibodies and there is a chance of an existing or past infection. It takes 14-21 days for the detectable amount of COVID-19 IgG to form. Statistics show that only 50% of the antibodies are in the blood in the first week after infection. About 90% in the second week and 100% in the third week. people. It has not yet been sufficiently investigated whether and to what extent antibodies have been formed against recurrent corona infection. It is currently unknown how long SARS-CoV-2 antibodies last after infection. Diagnosis of antibodies can be further complicated by false positive results. For example, a positive test result does not rule out the possibility of present or past infection with other coronaviruses. The test result may show antibodies formed in previously grown viruses and COVID-19. For these reasons, even after receiving a positive test result, it is necessary to continue to take all precautions: social distance, hand washing and personal protective equipment, wearing masks and gloves.
My test result (answer) is negative. What it means?
There can be several reasons for testing IgG-negative antibodies in COVID-19. First of all, you just do not get this virus and you do not have antibodies to this virus. Second, COVID-19 IgG antibodies may not have developed yet, so if you have had consistent symptoms of a viral infection in the last 3 weeks and a negative test, it is recommended that you repeat the test after two weeks.
But rarely, COVID-19 antibody testing can be negative even if you have or have had this viral infection. This condition occurs when the subject has a very low number of antibodies in the blood. Several groups of people with low levels of antibodies against the coronary virus could be distinguished.
- Patients who perform this antibody test in the early stages of the disease and in the immune system are still unable to produce antibodies.
- Patients with asymptomatic form of the disease.
- Patients who returned to COVID-19 infection but underwent antibody testing only after several months (during which antibody levels decrease naturally).
- Elderly patients with weakened immunity.
- People with very weak immune systems as well as patients taking immunosuppressive drugs.
Is COVID-19 IgG antibody testing alone sufficient?
IgG and IgM antibody tests are recommended for a clearer assessment of health status. IgM antibodies are usually produced earlier than IgG. In most patients, IgM antibodies develop approximately (3-7 days) after the onset of symptoms and are produced by both symptomatic and asymptomatic COVID-19 infection. Over time, IgM disappears and IgG remains in the blood and can be detected for several more months.
Why are the results obtained in different laboratories different?
Different laboratories may use different test methods and therefore the test results cannot be compared to the values obtained. It is also important to always evaluate not only the test results, but also pay attention to the patient’s symptoms, medical history, epidemiological information and other laboratory test results.
What does our experience show?
Although COVID-19 antibody testing is not currently recommended as a contraceptive, based on data from the Antja Laboratory, by 2020. Even 64 percent. The subjects who tested antibodies to COVID-19 decided to test prophylactically. Of those who tested COVID-19 IgG antibodies, up to 35% had positive results. Customers. Thus, every third customer who performed a preventive test also received a positive test result.
Meanwhile, among clients who felt symptomatic but did not experience or receive a negative result of the COVID-19 PCR test, antibodies generated in up to 62% were detected. people. And among the patients who confirmed the case by the COVID-19 PCR method, 13 percent. No COGID-19 IgG antibodies were detected in private individuals.
COVID-19 infection is a new challenge for medicine, so it is not surprising that there are questions and uncertainties in evaluating research results. Our lab data and the experience we have shown show that it is important to keep testing people and follow all the safety recommendations, only then can we overcome this difficult time together. So, if you think you have had a relationship or felt similar symptoms – do not delay!
Message from: Laura Belzewiczta, UAB Diagnostikos Laboratorija
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