The importance of tests for IgG, IgM, IgA antibodies in the diagnosis of infections

A laboratory test aimed at determining the amount of antibodies of three types (IgG, IgA, IgM) in order to assess the potential of a humoral immune response not related to the specificity of antigens. The analysis is prescribed during a comprehensive immunological examination. The results are used in immunology, infectious disease, oncology and surgery. Indications may include immunodeficiency conditions of various origins, long-term and recurrent infections, autoimmune and oncological diseases and postoperative complications. The level of immunoglobulins is determined in venous blood.

You can take a blood test for immunoglobulins at any time convenient for you. Check out the doctors' work schedule and choose a time that is convenient for you. Contact details and directions are on the contact page.

The level of total immunoglobulins IgG, IgA, IgM in the blood reflects the state of humoral immunity. Immunoglobulins are glycoproteins that are produced by B-lymphocytes during infection or the penetration of chemical compounds into the body that are recognized as dangerous. In the human body, there are 5 classes of immunoglobulins, each of which has its own characteristics in structure and function. Immunoglobulins IgG, IgA and IgM are responsible for the formation of the immune response during infection. By interacting with a foreign agent, antibodies neutralize it and enhance the lysis of the damaged cell. Also, during these reactions, the antigen is “memorized”; with repeated infection, antibodies are produced faster.

The analysis for immunoglobulins is a complex study; when interpreting its results, both each indicator separately and the total concentration of antibodies are taken into account. Immunoglobulins G are found in body fluids, make up about 80% of all antibodies, are produced after 5 days during primary infection, are able to “remember” the antigen and more actively protect the body during re-infection. Immunoglobulins A are found on the mucous membranes, protecting the respiratory and genitourinary tracts, and the gastrointestinal tract. They prevent antigens from penetrating deep into tissues. Immunoglobulins M circulate in the blood and lymph fluid, are produced immediately after infection enters the body and trigger an immune response.

A low level of immunoglobulins is determined by insufficient activity of the immune system. High levels may be a sign of hematological diseases and systemic pathologies. To carry out the analysis, blood is taken from a vein.

What are antibodies? And how to decipher the results of the analysis?

Antibodies are proteins that the immune system produces in response to infection. In laboratory diagnostics, it is antibodies that serve as markers of infection. The general rule for preparing for an antibody test is to donate blood from a vein on an empty stomach (at least four hours must pass after eating). In a modern laboratory, blood serum is examined on an automatic analyzer using appropriate reagents. Sometimes a serological test for antibodies is the only way to diagnose infectious diseases.

Tests for infections can be qualitative (they answer whether there is an infection in the blood) or quantitative (they show the level of antibodies in the blood). The level of antibodies for each infection is different (for some there should be none at all). Reference values ​​(normal values) of antibodies can be obtained with the test result. In the online laboratory Lab4U you can take a set of tests for all TORCH infections at one time and with a 50% discount!

Is express analysis possible?

get tested for antibodies at home. For example, Leccurate SARS-CoV2 Antibody Test allows you to independently perform a chromatographic immunoassay of blood. You can take it either from a finger or from a vein, although the second method is difficult to implement without a nurse. It is better to undergo express diagnostics for antibodies on an empty stomach . The kit includes a disposable lancet for puncturing the skin.

The blood is placed into the well of the test device, where it is mixed with a buffer liquid. The indicator reaction occurs within 10-20 minutes. Depending on the staining of certain areas, the presence of IgM, IgG or their absence can be detected.

Various classes of antibodies IgG, IgM, IgA

Enzyme immunoassay determines infectious antibodies belonging to various Ig classes (G, A, M). Antibodies to the virus, in the presence of infection, are detected at a very early stage, which ensures effective diagnosis and control of the disease. The most common methods for diagnosing infections are tests for IgM class antibodies (acute phase of infection) and IgG class antibodies (sustained immunity to infection). These antibodies are detected for most infections.

However, one of the most common tests - hospital screening (tests for HIV, syphilis and hepatitis B and C) does not differentiate the type of antibodies, since the presence of antibodies to the viruses of these infections automatically assumes a chronic course of the disease and is a contraindication, for example, for serious surgical interventions. Therefore, it is important to refute or confirm the diagnosis.

A detailed diagnosis of the type and amount of antibodies for a diagnosed disease can be done by taking an analysis for each specific infection and type of antibodies. Primary infection is detected when a diagnostically significant level of IgM antibodies is detected in a blood sample or a significant increase in the number of IgA or IgG antibodies in paired sera taken at an interval of 1-4 weeks.

Reinfection, or repeated infection, is detected by a rapid rise in the level of IgA or IgG antibodies. IgA antibodies have higher concentrations in older patients and are more accurate in diagnosing ongoing infection in adults.

A past infection in the blood is defined as elevated IgG antibodies without an increase in their concentration in paired samples taken at an interval of 2 weeks. In this case, there are no antibodies of classes IgM and A.

Is rapid testing reliable?

There are the following types of rapid tests : research using immunochromatography, using a set of reagents. In the first case, a person is asked to donate blood at a medical facility. The analysis has advantages:

• low price compared to PCR ;
• high speed (up to half an hour);
• ease of implementation.

However, its accuracy is questionable. Express analysis shows only the presence of components of the virus, and not the virus itself. Therefore, it is important to double-check all positive samples using the PCR .

With express kits (for example, Standard Q Covid-19), a person works himself . This is not an analogue of immunochromatography: blood is not needed here, a swab from the nasopharynx is enough. What exactly needs to be done is written in the instructions.

When the biomaterial comes into contact with the reagent, a coloring reaction occurs (as with pregnancy test This test for coronavirus is quite fast (up to 20 minutes), but not very accurate.

IgM antibodies

Their concentration increases soon after the disease. IgM antibodies are detected as early as 5 days after onset and reach a peak between one and four weeks, then decline to diagnostically insignificant levels over several months, even without treatment. However, for a complete diagnosis, determining only class M antibodies is not enough: the absence of this class of antibodies does not indicate the absence of the disease. There is no acute form of the disease, but it may be chronic.

IgM antibodies are of great importance in the diagnosis of hepatitis A and childhood infections (rubella, whooping cough, chickenpox), easily transmitted by airborne droplets, since it is important to identify the disease as early as possible and isolate the sick person.

References

1. Encyclopedia of clinical laboratory tests / ed. WELL. Titsa. - M.: Labinform, 1997. - P. 213-215, 223-226.
2. JVaillant, A., Jamal, Z., Ramphul, K. Immunoglobulin. In: StatPearls, 2021.
3. Sathe, A., Cusick, J. Biochemistry, Immunoglobulin M. StatPearls Publishing, 2021.
4. Histology (introduction to pathology) / ed. E.G. Ulumbekova, Yu.A. Chelysheva. - M.: GEOTAR-Media, 1997. - P. 528 – 530.
5. Kumar, V., Abbas, A., Fausto, N. et al. Robbins and Cotran Pathologic Basis of Disease, 2014. - 1464 p.

IgG antibodies

The main role of IgG antibodies is the long-term protection of the body from most bacteria and viruses - although their production occurs more slowly, the response to an antigenic stimulus remains more stable than that of IgM class antibodies.

Levels of IgG antibodies rise more slowly (15-20 days after the onset of illness) than IgM antibodies, but remain elevated longer, so they may indicate a long-standing infection in the absence of IgM antibodies. IgG may remain at low levels for many years, but upon repeated exposure to the same antigen, IgG antibody levels rise rapidly.

For a complete diagnostic picture, it is necessary to determine IgA and IgG antibodies simultaneously. If the IgA result is unclear, confirmation is carried out by determining IgM. In case of a positive result and for an accurate diagnosis, a second test, done 8-14 days after the first, should be checked in parallel to determine the increase in IgG concentration. The results of the analysis must be interpreted in conjunction with information obtained in other diagnostic procedures.

IgG antibodies, in particular, are used to diagnose Helicobacter pylori, one of the causes of ulcers and gastritis.

What else is prescribed with this study?

Humoral immunity (immunoglobulins IgA, IgM, IgG, IgE, circulating immunocomplexes, complement components C3, C4)

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Immune status (screening) (Phagocytic activity of leukocytes, cellular immunity, total immunoglobulin IgE, immunoglobulins IgA, IgM, IgG)

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Total immunoglobulin IgE

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Cellular immunity (T-lymphocytes, T-helpers, T-cytotoxic cells, Immunoregulatory index, B-lymphocytes, NK-T cells, NK cells, Leukocyte formula)

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Serum paraprotein typing using immunofixation

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Antibody analysis in the diagnosis of TORCH infections

The abbreviation TORCH appeared in the 70s of the last century, and consists of capital letters of the Latin names of a group of infections, the distinctive feature of which is that, while relatively safe for children and adults, TORCH infections during pregnancy pose an extreme danger.

The blood test for TORCH infection is a comprehensive study, it includes 8 tests:

— Determination of antibodies to herpes simplex virus type 1,2 IgM and IgG

— Determination of antibodies to cytomegalovirus IgM and IgG

— Determination of antibodies to the rubella virus IgM and IgG

— Determination of antibodies to Toxoplasma gondii IgM and IgG

Often, infection of a woman with TORCH complex infections during pregnancy (the presence of only IgM antibodies in the blood) is an indication for termination.

General information

IgG makes up up to 80% of all immunoglobulins contained in serum, and up to 20% of its total proteins. They produce IgG plasma cells (mature B lymphocytes).

Class G immunoglobulins provide the body's secondary humoral response to infection. That is, first, class M immunoglobulins (“alarm antibodies”) are produced in response to foreign cells in the body, and only after 5 days do G antibodies (IgG) appear. Their half-life is 23-25 ​​days. This means that throughout this time the body is actively “fighting” the disease, as a result of which its resistance to the disease increases.

Normal value for immunoglobulin G

The following reference values ​​have been established for IgG:

Note: It should be noted that each laboratory has the right to establish its own range of normal values. It is advisable to take tests and undergo treatment at the same medical institution.

Factors of influence

There are factors that can distort test results:

• intense sports activities;
• excessive stress and worry;
• taking alcohol or drugs, smoking;
• long-term use of drugs to enhance immunity;
• taking certain medications: carbamazepine;
• phenytoin;
• methylprednisolone;
• hormonal drugs (estrogen, oral contraceptives);
• valproic acid;
• gold preparations;
• cytostatics;
• immunosuppressants (drugs for artificial suppression of immunity);

It is advisable to assess the state of general immunity and diagnose pathologies after a comprehensive study of immunoglobulins of all classes.

Where can I get a blood test for immunoglobulin inexpensively and quickly?

Today, many medical institutions in St. Petersburg invite you to take an immunoglobulin test, but not every clinic can boast of the efficiency of conducting the study. If you need a high-quality immunoglobulin examination in a short time, contact the RIORIT medical clinic. A modern diagnostic laboratory is at your service, as well as qualified doctors who will provide comprehensive advice on issues that interest you. You can find out more about prices for immunoglobulin testing, find out about discounts and make an appointment in the treatment room for testing by phone. or at the address of our clinic: St. Petersburg, Kalininsky district, st.
Rustaveli 66G (metro station Grazhdansky Ave. or Devyatkino). MRI and ultrasound center RIORIT

Area:

Kalininsky

Metro:

metro station Grazhdansky Prospekt, metro station Devyatkino, metro station Prospekt Prosveshcheniya

Address:

St. Petersburg, Kalininsky district, st. Rustaveli, 66 lit. G

Telephone:

Equipment:

Siemens, open type

Schedule:

Around the clock

What is the "positivity rate"?

Semi-quantitative tests are used in most cases to determine antibody levels after vaccination. They do not show the exact amount of antibodies formed. But with their help, you can assess the intensity of the immune response - by the brightness of the sample, if the test is carried out using the enzyme-linked immunosorbent assay (ELISA).

Tests from different manufacturers have different scales. In most cases, state laboratories use Vector-best test systems, and their cut-off level is 1. That is, if the indicator is lower, there are no antibodies. From 1 to 1.1 is the so-called gray zone. If the result is higher than 1.1, it means that we have a strong positive reaction of the immune system.

The “positivity rate” shows how many times the level of antibodies in the sample exceeds the threshold level for their recognition. So, for example, the indicator of 15, which the president recently spoke about, is a good result. The majority of those vaccinated with Sputnik V or CoviVac have approximately the same or even higher rate of positive immune response.

At the same time, I would like to note once again that other test manufacturers may have a different scale and, accordingly, different indicators. At the same time, when you receive the test result in the laboratory, you can always see the reference values ​​on the form and compare the result with them.

Shpakovskaya district hospital

Petr Chumakov: “There is no need for high levels of antibodies”

Is vaccination against COVID-19 necessary? Which vaccine do you prefer? How do the antibodies that are produced as a result of the disease differ from those that should appear after vaccination? Will they protect and protect you for long? This is our conversation with Pyotr Mikhailovich Chumakov, chief researcher at the V.A. Institute of Molecular Biology. Engelhardt of the Russian Academy of Sciences, corresponding member of the Russian Academy of Sciences.

– Pyotr Mikhailovich, today three vaccines against the new coronavirus infection have already been registered in our country. Which one should you choose?

– Indeed, formally we now have three vaccines registered. Although Sputnik V, of course, is significantly ahead. Firstly, because it was the first registered vaccine, and, in addition, behind the development of Sputnik there is many years of work by a team that creates such vector vaccines based on adenovirus. The choice to use it as the first choice vaccine is quite understandable. It could have been created in the most emergency mode, which is what happened.

The following can be said about the other two vaccines. EpiVacCorona – development of Novosibirsk “Vector”, peptide vaccine. This is a new type of vaccine, and there is still very little experience with its use. Their effectiveness is little known. I would say that this project is experimental. The biggest expectation was that it should not have major side effects. Therefore, if it is effective, it will be the vaccine of choice for frail elderly patients. But now I can’t say anything about this vaccine, because there is no data on its effectiveness. I just want to say that publicly available tests for antibodies and S-protein after vaccination in the experimental group show the absence of antibodies. At the same time, Vector has its own test system that allows you to monitor the formation of antibodies against these peptides, and this system shows that antibodies appear. It is not clear to me how this can be, and this issue requires clarification. Therefore, I think that this vaccine is not yet ready for mass use, and you should not count on it as a life-saving vaccine that can protect against the disease.

– What can you say about the vaccine, recently registered, which was manufactured at the scientific center for immunobiological preparations, named after your father?

– This is a traditional vaccine, which includes the production of a large amount of a pathogenic virus, which is then inactivated in a certain way. This is the so-called “killed” vaccine.

This kind of vaccine is most often used, so there is a lot of hope for this particular one, because unlike Sputnik V, which causes the formation of antibodies to only one S-protein, although the most important, but, nevertheless, only one, Such “killed” vaccines produce antibodies to all proteins of the virus. And therefore, it is possible that immunity after vaccination with CoviVac will be more durable and versatile. Although, again, today there is no available data about this vaccine. Therefore, for now, I would only recommend it as a second choice vaccine. I would wait for mass application until we become familiar with its parameters. – Many people think that imported vaccines are a priori better than domestic ones. Is this really true or are our vaccines no worse?

– In this case, this cliché is completely inappropriate. I must say that vaccinology and virology in our country have always been at their best. The first virus was discovered in Russia by D.I. Ivanovsky. We were ahead of many countries. Of course, the amount of money invested in our science cannot be compared with what happened and is happening, for example, in America and Europe. However, our scientists are highly motivated and well trained. And we know how to win. The same Sputnik vaccine, developed at the Research Center for Epidemiology and Epidemiology named after. N.F. Gamaleya is the fruit of efforts spanning many decades. Such work began in the USSR back in the early 70s, when adenoviruses were studied, then they began to make various kinds of vectors from them. An Ebola vaccine was developed using this platform. Therefore, I believe that there is no doubt that everything here is done with high quality. The results, published in two Lancet papers, suggest the vaccine has worked.

As for foreign analogues. Indeed, we often treat with reverence everything that comes out of the West. But there are also a lot of problems there – both organizational and medical.

For example, the AstraZeneca vaccine is also a vector vaccine, made on the basis of a monkey adenovirus. This is good, because humans do not encounter the monkey virus. But, nevertheless, it now turns out that the AstraZeneca vaccine reacts poorly and does not protect well against the South African variant of the coronavirus, while Sputnik protects well. And this is one of the arguments why AstraZeneca, together with the Institute. N.F. Gamaleya is now making a hybrid vaccine, which will be used in some countries.

As for vaccines based on the mRNA platform, which have high hopes, this is also a new class of vaccines. I was initially very skeptical about this choice to develop a vaccine that should stop the pandemic as soon as possible. The RNA that is part of this vaccine degrades very easily under the influence of various factors, and it is very difficult to predict everything. For example, if the temperature regime is not very well maintained, it is not clear whether it will be effective in “field” conditions? It’s one thing when this is a trial and all its participants are anxious about following the protocol. What will happen when mass vaccination begins? There must be very powerful logistics, and refrigerators that will provide very low temperatures.

As for the vaccine itself, in principle, it showed good results during testing. But now there are very conflicting reviews about this vaccine regarding possible side effects. There are reports of severe side effects and even deaths. It is worth investigating whether these cases are actually related to the use of the vaccine. This issue certainly needs to be carefully studied.

Another doubt raised is that this vaccine uses a polyethylene glycol-based formula as a carrier, stabilizing agent. There have been reports that this formulation itself may induce the formation of antibodies that will prevent vaccines on the same platform from being used against other diseases in the future. There are also concerns that polyethylene glycol may cause additional adverse reactions in some people.

– Pyotr Mikhailovich, in Moscow there is now mass vaccination with Sputnik in shopping centers and other crowded places. we are not talking IgM and IgG antibodies People just come from the street and get vaccinated without checking. Although we know that someone could have been ill asymptomatically, and they may have high antibody titers. Do you think it’s dangerous to get vaccinated without such testing?

– In principle, there is nothing wrong with this. If we take into account the economic aspect, we must understand that these tests are quite expensive. If they are performed on everyone, the procedure will become significantly more expensive. Does this make sense from a medical point of view? There is no clear answer here either. Firstly, any test gives errors. It may be that the person has not been ill, but has a false positive result, or, conversely, the person has been ill, but the test shows nothing. Therefore, I think that in any case one should be vaccinated, even if a person has been ill, especially in a mild form.

- What if it’s heavy?

– If he was seriously ill, we should probably wait. There is currently no reliable evidence that you can become seriously ill after suffering the disease again. I think that those who have actually been ill should not get vaccinated now. Everyone else who doubts, even if they have not been tested, should be vaccinated.

– But vaccination may be useless if a person, for example, has high class G immunoglobulins. Why expose your body to unnecessary stress? Still, vaccination is not a vitamin drink.

– If you had a certain level of antibodies, and you get vaccinated, this is called a boost in immunology - a powerful addition of antigen already against the background of the fact that there was a primary response. At the same time, the level of antibodies will rise very strongly. There's nothing wrong with that. This does not pose any danger, but the protection may be longer.

— Many are afraid of such a serious complication of vaccination as antibody-dependent enhancement (ADE). What is this condition and how to insure yourself against it?

“Indeed, at first the possibility of ADE occurring during coronavirus infection raised concerns. The nature of this phenomenon lies in the negative effect of antibodies that are produced against viral components, but bind to it without causing inactivation of the virus. This complex of virus and antibody is absorbed by cells, for example macrophages, which normally remove foreign products from the body, but in this case they lead to the spread of the virus throughout the body and cause an increase in infection. This scenario is also possible if the quality of the viral antigen in the vaccine is poor, when antibodies are formed that do not bind strongly enough to the virus. Fortunately, we have not yet seen any confirmed cases of this kind. But, although this issue is not completely closed, this should not be a strong argument against vaccination, especially against vaccination with Sputnik, which causes antibodies in response to the intact S protein produced by the viral vector.

– The next question is important for many. People sign up for antibody testing at a regular district clinic and see the following information: in this way you can check whether you have been sick, including asymptomatic ones, or are sick now. But you cannot find out the level of antibodies resulting from vaccination. The question arises: why? Are these some kind of different antibodies?

– Of course, these are different antibodies. The fact is that the test for past illness is a test for the N-protein, which is located inside the virus, not on its surface, and antibodies to it arise when a person encounters this virus and gets sick. But if you use this test to check the formation of antibodies after vaccination with Sputnik V, it will not show you anything.

– So this class of antibodies is not produced as a result of vaccination?

- Yes, it’s not being produced. As a result of vaccination, antibodies are produced only to the S-protein, the surface spike, which, in fact, ensures the neutralization of the virus and the binding of these antibodies to the spike. In order to check how you developed antibodies specifically for vaccination, you need to go to companies that do such a test. There are such companies. For example, Helix, which offers a quantitative test that can be used to determine the amount of antibodies, that is, to see how successful the reaction to vaccination was.

– We know that antibodies are not always produced in everyone, either as a result of illness or as a result of vaccination. There are people who are immune to both vaccination and certain viruses in general. And so, let’s say a person was vaccinated, but he did not develop antibodies. What conclusion can he draw from this - that he is still not protected from the disease and he needs to take some measures or, on the contrary, he is protected and this virus does not threaten him?

– In most cases, it all depends on how much time has passed since vaccination. If, for example, a month and a half has passed since vaccination, then almost everyone will probably have a sufficient level of antibodies. Although the publication in The Lancet, published by the authors of Sputnik, shows that after the second vaccination there are people whose increase in antibody levels is not so pronounced, nevertheless, the production of antibodies is observed. I agree with the authors that this level is enough to prevent a person from becoming seriously ill. If antibody levels still remain low, I think it is worth considering a booster shot with a different vaccine.

- Exactly the other one?

– You should not be vaccinated with the same vaccine, because there are already antibodies to the adenovirus, and perhaps this vaccination will not be effective. After all, the titer of antibodies to the adenoviral vector will be very high soon after vaccination, and this may interfere with vaccination. But everyone is different, and the immune system reacts to everything differently. Some may have had concomitant diseases during vaccination that were not paid attention to, but which prevented the formation of antibodies. Of course, we must not forget about this. This also applies to frequently ill, weakened people, and elderly people whose immune system is also not up to par. Probably in this case it makes sense to find out how well the antibodies have formed.

The second aspect is if quite a long time has passed after vaccination, and the antibodies have dropped and are not even detectable. This also doesn't say much. Usually after vaccination, even after a previous illness, the level of antibodies initially rises, but then falls, but there is no need for high levels. If there had not been such a decrease, we would have had solid antibodies in our blood from all the previous encounters with antigens.

Low levels of antibodies over time do not mean that a person is not protected, because he still has memory cells that store information about these antibodies. And as soon as a person encounters the virus again, they begin to multiply very quickly and produce these antibodies. The incubation period, which always occurs during infection, is usually sufficient for the required amount of antibodies to develop during this time.

Although much is still unknown. For example, it is not clear what will happen if a person is faced with a huge dose of the virus? Will vaccination help overcome the existing antibody barrier? Maybe not. But I think, in any case, a person will suffer from a milder form of the disease.

– In what case should a person decide that perhaps it is worth trying to be vaccinated with another vaccine, since antibodies are low?

– If 45-60 days after vaccination the antibodies are still low or absent, you probably need to be vaccinated with another vaccine. Of those that I would now recommend, this is the vaccine from the center. M.P. Chumakova.

– What kind of vaccine did you choose for yourself, or are you still making do with those non-specific means of prevention that, following your wonderful parents, you continue to develop?

“I protected myself this way throughout the entire pandemic, but now I still decided to get vaccinated because I believe in Sputnik.” I know the people who worked on it well. Publications on this topic are quite convincing. That's why I got vaccinated. I haven't checked my antibody levels, although it might be worth doing. Now just about three weeks have passed since the second vaccination. I feel protected. Although this does not mean that you have to go to great lengths and communicate with the sick. I have always had a certain skepticism regarding the mask, but, nevertheless, since such an order exists, we must follow it. I don’t know whether this is effective or not, but I think it is effective to some extent, because this year, for example, there was no flu epidemic.

– Do you think there was no flu because they wore masks, and not because flu and Covid are competing viruses?

- Well, what competition is there! If, let’s say, this virus circulated widely and did not cause painful symptoms in most people, then yes, it would probably be competition. And in this case, when a person encounters a virus, in most cases he gets sick. So I don't think it's competition. Most likely, precautionary measures played a decisive role here - distance, absence of close contacts, and masks. All this has led to the fact that there is practically no flu this year.

In what cases is a paid IgG test for Covid-19 carried out?

Testing is indicated in the following situations:

1. Identification of the acute stage. Immunologists and therapists recommend testing IgA, IgG and IgM antibodies separately. It is also necessary to monitor the detection of proteins over time. If the results remain unclear, the test is repeated after a week.
2. If it is necessary to divide patients into categories: those who have already been ill and those who are experiencing the acute phase of the disease.
3. If necessary to rule out infection. In this case, rapid testing or point-of-care screening is indicated.
4. If hidden carriers of coronavirus infection are identified, with an asymptomatic course.
5. If an epidemiological investigation is carried out, it is necessary to identify patients who have had the infection.
6. If you need to identify plasma donors that would help in the treatment of patients in the acute phase.

Also, a rapid test for COVID is important for categories of people who find themselves in the following circumstances:

• returns from countries with high levels of virus incidence;
• return from regions with high infection rates;
• potential infection through contact with carriers or people with a confirmed diagnosis;
• presence of ARVI symptoms;
• suspected pneumonia;
• increased body temperature;
• suspicion of previous infection.

What test can be done before vaccination?

Currently, IgG antibody tests are most often performed by people about to get vaccinated to ensure they have not previously had COVID-19 asymptomatically or have naturally acquired immunity. If the test shows a positive IgG antibody titer, vaccination can be postponed.

What if a person wants to check the level of antibodies after vaccination? Now many people compare their performance.

You need to understand that the tests used in laboratories are different and the scales they use are also different. Therefore, if you try to compare results (although there is not much point in this), then you must at least be sure that you tested with the same test.