Total antibodies to coronavirus and what is it

2024 Author: James Gerald | [email protected]. Last modified: 2023-12-17 14:00

In connection with the spread of the pandemic, the question of diagnosing COVID-19 arises. Many people want to know whether they were sick or not, because the disease is mild and asymptomatic, but after receiving the test results, new questions often arise. Total antibodies to coronavirus: what is it and how to decipher the results?

What is total antibodies to coronavirus

Antibodies are large protein molecules. They begin to be produced by immune cells in response to infection. Then they carry out the fight against the virus, remember it, and at the next meeting with the infection, they protect the body.

A blood test for antibodies to COVID-19 shows whether a person has encountered this infection or not. In case of coronavirus disease, an analysis is made for three types of immunoglobulins:

1. IgM begins to be produced first at the very beginning of the infectious process, reaching a maximum value in the acute phase of the disease. Then they begin to decline, and in the process of recovery they disappear completely. These antibodies reach their maximum values after about 7-10 days. A positive result indicates that the person has become infected and is in the acute stage of the disease.
2. IgA is the first to fight viruses. Their rate increases on the second day from the onset of the disease, and after a while these antibodies disappear along with IgM.
3. IgG also begins to be produced during illness, but the highest blood count occurs 10-14 days after a person is ill. They indicate a stage of recovery or that a person has already suffered from COVID-19. Immunoglobulins G last for several months and protect the body from re-infection.

The test for total antibodies to coronavirus IgM, IgA, IgG refers to new diagnostic methods. Comprehensive testing for IgM, IgG is more often done, but in some laboratories it is possible to pass an analysis for all three types of immunoglobulins. It points with 100% accuracy to antibodies directly to COVID-19, and not to other types of viruses.

Such a test will help establish the correct diagnosis even in controversial situations. And after the introduction of the vaccine, using the analysis, the change in the level of antibodies is observed to determine the stability of the immunity.

The analysis is taken in the morning on an empty stomach. If you need to donate blood during the day, then you must refuse to eat 3-4 hours before the test and do not smoke for 30 minutes.

What is the total antibody test for?

An analysis for specific immunoglobulins is needed for mass testing to find out how well the population immunity is formed. This will help to adjust the timing of the removal of restrictions, as well as:

• identify asymptomatic carriers of the infection;
• clarify the diagnosis if COVID-19 is suspected, but with a negative PCR test;
• establish the fact that the person has already been ill;
• to identify carriers of the infection who arrived from foreign trips.

Testing only for immunoglobulins M can show a false positive result, since IgM antibodies are produced in various acute and chronic inflammations, endocrine and autoimmune diseases. Immunoglobulins A are synthesized in the acute phase of the disease in response to the penetration of coronavirus into the mucous membranes of the nose and throat.

In the process of recovery, their concentration decreases. Last of all, immunoglobulins G are produced. After COVID-19, they persist for several months. Determination of all classes of immunoglobulins at once makes the test more sensitive, so you need to take a comprehensive analysis.

Unlike the PCR test, which is done at the very beginning of the disease, the analysis for total antibodies to coronavirus is taken no earlier than 2 weeks after the onset of symptoms.

Interpretation of analysis results

In the acute phase of the disease, a PCR test is considered more relevant, therefore, antibody tests are not done. They are usually prescribed no earlier than 14 days after the onset of the illness, in order to establish exactly whether a person was sick with COVID-19 or not.

Decoding the results:

1. IgM, IgA, IgG antibodies were not detected. This result means that the person has not encountered COVID-19, or the disease is in its initial stage, when immunoglobulins have not yet been produced.
2. Only IgM was found. This means that the person is sick at the moment or is in the process of recovery. Immunoglobulins M are also produced in asymptomatic patients. Here it is necessary to take into account that IgM is found in the blood for chronic ailments not associated with COVID-19. As a result, the analysis may be false positive.
3. Detected IgM and IgG. This indicates that the patient is beginning to recover or has just been ill.
4. Found only IgG. The result means that the person had a coronavirus infection at least 2 weeks ago. These antibodies persist even after complete recovery.

Only a doctor can correctly decipher the results of the analysis and explain what each indicator means.

IgA antibodies

The result of the analysis for immunoglobulins A is positive if the indicator is greater than 1, 1. This indicates the presence of infection in the body, including in asymptomatic patients. The indicator from 0, 8 to 1, 1 is considered borderline, speaks of the initial stage of the disease. In this case, retesting is recommended after 2 weeks.

A result less than 0.8 indicates the absence of IgA. This means that the person has not been infected with COVID-19 or is at the very beginning of the disease, when antibodies have not yet formed. In the early stages, the index of immunoglobulin A is more specific, therefore it is more accurate than IgM.

IgG antibodies

The result is positive if IgG is greater than 1, 1. This indicates already formed immunity, if immunoglobulins of class M and A are not detected, or the formation of immunity and the recovery phase, if there are additionally IgM or IgA antibodies. Borderline values from 0, 8 to 1, 1 can be if less than 5 weeks have passed since the onset of the disease. They mark the beginning of IgG formation and require retesting after 2 weeks.

Retesting is more likely to be positive. The result is negative if the indicator is less than 0.8. This means that the person has not met with COVID-19 or is in the acute phase of the disease. If there are symptoms of coronavirus, then a PCR test and tests for IgM, IgA are prescribed. The presence of IgG antibodies always indicates an immune response to the coronavirus and is considered a sign that a person has had an infection.

Outcomes

Immunoglobulins begin to be produced by immune cells in response to infection. Antibodies IgM, IgA, IgG are synthesized at different stages of the disease, so it is important to do comprehensive testing. The doctor will help to correctly decipher the results, who will take into account the results of the examination and the patient's complaints.