SARS-Cov-2 coronavirus test for IgG antibodies

COVID-19 coronavirus test testing for IgG antibodies

What is the anti-SARS-COV-2 serological test?

• The test detects IgG antibodies in venous serum, which occur as a result of contact with the virus. Antibody determination is performed by the semi-quantitative method.
• The tests used in our laboratories are certified for use on humans for diagnostic purposes.
• After purchasing the test, just come to the Medical Center where the test was purchased.

COVID-19 coronavirus test (IgG antibodies test) - when to have it done?

• determinations of the combination of IgG and IgM antibodies should be performed not earlier than on the 15th day after the onset of COVID-19 symptoms (i.e. cough, fever, dyspnoea);
• for epidemiological studies to determine the spread of infection;
• to detect people who have had an asymptomatic or low symptomatic case;
• to test those who have recovered to obtain plasma for therapeutic purposes;
• for retrospective epidemiological studies to detect people who have had contact with the virus and have been able to develop immunity mechanisms.

Determination of anti-SARS-COV-2 antibodies by semi-quantitative method

The serological test for anti-SARS-CoV-2 antibodies determines the patient's IgG antibody titre.

It aims to assess changes to antibody concentration over time, which may be useful in the epidemiological process.

Important information: Patients showing symptoms of covid-19 (high fever, cough, shortness of breath, muscle pain, weakness) should immediately contact the nearest sanitary-epidemiological station by phone or report to a hospital for infectious diseases.

How to interpret the coronavirus test results?

Determining anti-SARS-CoV-2 antibodies is a complementary test and should not be performed to diagnose an active infection. Confirmation of the infection requires molecular testing and detection of the genetic material of the virus.

Not detecting antibodies does not rule out SARS-CoV-2 infection. The test may have been performed while the antibodies were not yet present or their level was too low (so-called serological window). The test should be repeated after 2-4 weeks.

The results of the serological test should be interpreted in conjunction with clinical signs and/or epidemiological medical history.

Detection of antibodies may indicate that the infection has passed or is still active. The presence of antibodies can also be caused by infections from other microorganisms, diseases in which autoantibodies are produced, or vaccination against influenza. Molecular testing is recommended to definitively confirm SARS-CoV-2 infection.

IgG antibodies are detected after about 21 days or later. There is no reliable information yet on how long the antibodies will circulate after infection. Based on experience with other coronaviruses, it can be predicted that IgG antibodies will be detected for at least several years after the disease.

Waiting time for the test result:

• at Synevo Blood Collection Points you will receive the result of the test within 24 hours, with a maximum waiting time of 3 working days for the test result,
• at the Damian Medical Center and Medicover Medical Center, the waiting time for the test result is up to a maximum of 2 working days.

If you want to consult the results of the examination with a doctor, use a telemedicine consultation with an internist. If you sign up for MediClub you will benefit from a 5% discount.

FREQUENTLY ASKED QUESTIONS:

What is the difference between IgG and IgM antibodies?

The concentration of serum IgM antibodies increases in the first days of infection and then gradually decreases. Therefore, their presence indicates the early stage of infection caused by SARS-CoV-2. In turn, IgG antibodies are referred to as so-called late-stage infection antibodies. The presence of IgG antibodies alone indicates that the infection occurred earlier than a few weeks ago.

When is it better to determine IgG and when IgM?

Antibodies begin to be produced approximately 1-2 weeks after the onset of the symptoms. Antibody tests for IgM and/or IgG are usually performed about 2-3 weeks after the COVID-19 symptoms appear – at this stage, their concentration is the highest. Serological tests that are performed too early may give a false negative result due to the so-called serological window, i.e. the period of time when antibodies are not yet detectable.

When is it worth doing the antibody test?

Antibody testing is especially recommended to identify individuals who have had COVID-19 in either asymptomatic or oligosymptomatic form, or if the patient had symptoms of a respiratory infection but did not perform the test to confirm SARS-CoV-2 infection. The antibody testing allows the identification of the so-called convalescents who can donate plasma to help other sick people.

When to propose the IgG + IgM combination test? Is it more reliable/accurate/ better than single IgG and IgM tests?

The detection of IgM and IgG antibodies suggests that the infection took place in the last few weeks. The sensitivity and specificity of this test (i.e. its reliability) varies depending on the timing. It was determined that the reliability of the combined IgM and IgG tests was the highest when it was performed on days 22-35 from the onset of the symptoms, as well as on days 15-21. At all analysed time points, its sensitivity was higher than for single antibody tests (Cochrane, 2020).

Are the tests results recognised by the National Health Fund if someone wants to donate plasma?

The convalescents are required to confirm, or at least strongly prove, the actual history of SARS-CoV-2 infection. For instance, positive result of the quantitative test of anti-SARS-CoV-2 IgG class antibodies is considered to be sufficient evidence of a SARS-CoV-2 infection. Semi-quantitative tests are available at Medicover.

What does the semi-quantitative method mean?

The semi-quantitative test differs from the qualitative test in that it both detects IgG and IgM antibodies and also allows to determine the level of these antibodies. However, it is not a method as accurate as quantitative test that assesses the titer (amount) of antibodies in the plasma. For more detailed information, please visit the Synevo laboratory website: https://www.synevo.pl/test-na-przeciwciala-koronawirusa-polilosciowo/.

Are these tests recognised when travelling and crossing the border?

Due to the current epidemic situation, the Ministry of Foreign Affairs recommends to avoid traveling abroad especially when it is not absolutely necessary. The conditions to be met by a person crossing the border of a given country differ between countries – before planning a trip, please read the information on https://www.gov.pl/web/dyplomacja/informacje-dla-podrozujacych. If a negative SARS-CoV-2 infection test result is required before you are allowed to enter a country, it is usually a PCR test result (nasopharyngeal swab) – not an antibody test.