SARS Cov-2 IgG

The SARS-CoV-2 IgG analysis is a serological test that detects IgG antibodies to the spike protein of the SARS-CoV-2 virus in serum and plasma. These antibodies indicate the body’s adaptive immune response to the coronavirus, which may suggest a recent or previous infection. The test is based on the ELISA method and is conducted using approved kits with established standard operating procedures. The Belgrade laboratory, IntroLab, allows you to perform this type of immunological analysis in modern facilities in the heart of the city.

Why is this analysis performed?

This analysis allows the detection of the body’s natural immune response to the COVID-19 virus. It can also help assess the immune response following vaccination.

Importance of the SARS-CoV-2 IgG Test

It often happens that someone contracts the coronavirus without knowing it. This happens because not every carrier of the virus will develop symptoms. That said, tests for the presence of IgG antibodies in the blood can help healthcare professionals better understand how common the virus is.

How does the test for the presence of virus IgG antibodies work?

The antibody test, also known as a serological test, searches for their presence in the blood. When your body fights an infection, such as COVID-19, it creates IgG class antibodies. The same happens when you receive a vaccine. Accordingly, the antibody test does not check for the virus itself but checks whether your immune system has reacted to the infection.

Difference between PCR test and antibody test

The coronavirus test, or PCR test, looks for signs of active virus. It is simpler than the serological test. However, it only shows whether you have the virus in your body at the time of testing. On the other hand, the antibody test shows that you have had the virus at some point in the past.

When is this analysis indicated?

Indications for testing for SARS-CoV-2 IgG antibodies include:

• Suspected previous infection: Individuals who have had COVID-19-like symptoms in the past but were not tested for active virus can be tested for antibodies to confirm a previous infection.
• Checking immune response after vaccination: Antibiotic testing can help assess the body’s immune response after receiving a coronavirus vaccine.
• Asymptomatic infections: Individuals who have been in close contact with an infected person but have not developed symptoms can be tested to determine if they were truly asymptomatic cases.
• Plasma donation: Individuals who have recovered from the disease and wish to donate their plasma for the treatment of other patients can be tested for antibodies to confirm their immune status.

How to prepare for the analysis?

No special preparation is required for the SARS-CoV-2 IgG analysis. Blood is drawn in the laboratory, and the sample is sent for analysis.

How are the results interpreted?

• A negative result (<50.0 AU/mL) does not rule out SARS-CoV-2 infection, especially in people who have recently been in contact with the virus. In such cases, additional testing by the PCR method is recommended.
• A positive result (≥50.0 AU/mL) may indicate that the person had a COVID-19 infection weeks or months before testing and may have developed immunity.

Antibody results should not be the only basis for diagnosing or ruling out SARS-CoV-2 infection. Also, it is not scientifically confirmed whether the presence of antibodies against the COVID-19 virus protects against reinfection.

Disease prevention

Preventive measures include wearing masks, maintaining physical distance, washing hands, and vaccination.

After the analysis

If the result is positive, consultation with a doctor is recommended for further advice and possible monitoring of health status.

Related analyses

In addition to the SARS-CoV-2 IgG analysis, IntroLab Laboratory Belgrade also offers an analysis for the presence of SARS-CoV-2 IgM antibodies. This analysis detects IgM antibodies that usually appear earlier after infection and indicate an active or recent infection. They are the first line of defense and appear before IgG.