How antibodies are formed
There are currently two main types of tests associated with coronavirus infection. These are tests that allow you to establish the very fact of the disease and the presence of the virus in the body. This category includes a PCR test and a rapid test for the detection of antigen for coronavirus. Such studies can detect coronavirus in the body even if the symptoms are mild or absent altogether.
Another type of test is antibody testing. They are carried out in order to understand whether the body has encountered a coronavirus infection in the past and even roughly determine how long ago this happened.
Antibodies are molecules that are synthesized in the body in response to an infection. Another name for these molecules is immunoglobulins, and the abbreviation Ig is used in test forms and scientific publications.
Antibodies perform a protective function. Immunoglobulins M (IgM) are first encountered with an infectious agent, and their presence is the very first sign of infection. The concentration of IgM increases in the first days of the disease, and then gradually decreases – after a month it will most likely not be possible to detect them. Although some of those who have had a coronavirus infection, immunoglobulins M can circulate for a long time – up to several months.
Antibody Classes: What They Indicate
A little later – about 2-4 weeks after the coronavirus enters the body – the synthesis of antibodies of another type begins – immunoglobulins G (IgG). They persist for a long time, in some cases for life. The presence of IgG in the absence of IgM is a sign that the patient has had the disease some time ago, but now the acute phase is over. The simultaneous presence of antibodies of two types – both IgG and IgM – indicates that the person is recovering, the active phase of the disease has passed.
In addition, protective antibodies of class G will be formed after vaccination, the concentration of IgG after the vaccine will increase. It is necessary to check their level not the next day after the introduction of the vaccine, but a couple of weeks after the completion of the vaccination cycle – for most currently approved vaccines, it consists of two stages.
IgG are produced to different viral proteins – after the disease, two types of antibodies may appear: to the N-protein and to the S-protein, the latter are considered more important in preventing re-infection. After vaccination, most vaccines synthesize precisely IgG antibodies to the S-protein, their presence indicates acquired immunity. Antibody quantification test systems used around the world produce results in a single format – internationally recognized units (BAU / ml), which allows you to compare different results with each other and evaluate the change in antibody levels over time for those who are interested.
When is an antibody test optional?
Experts from the World Health Organization do not consider the level of antibodies to be a significant indicator by which one can determine whether the body is sufficiently protected from re-infection. The specialists of the Russian Ministry of Health are of the same opinion – they recommend vaccinating six months or a year after the illness or vaccination, and it is not necessary to take an antibody test before that.
Currently, researchers do not have data on what exactly the level of antibodies should be in order to provide protection against infection. However, scientists from St. Petersburg in 2021 showed that re-vaccination in those who have already been ill or have been vaccinated causes a faster increase in the concentration of antibodies – in this case, the body’s defenses will be mobilized faster.
How to become a plasma donor if there are a lot of antibodies
We add that if you yourself have passed the ELISA test and received a result in terms of the number of titers: IgG ≥ 150 and IgM ≥ 0, then you can become a plasma donor. It is used in the treatment of patients with moderate and severe forms of coronavirus infection who are in hospitals. During the use of immune plasma, its clinical effectiveness has been proven: in moderate patients, the chance of being in intensive care, on mechanical ventilation, is reduced by 63%. And the probability of recovery of seriously ill patients who receive plasma increases by 19%. These figures are available on the mos.ru website.
Any Russian citizen between the ages of 18 and 55 can donate blood for plasma. Of course, there are a number of contraindications that you can check on the websites of city blood transfusion centers. Your blood will be carefully checked before it is used. By the way, donation is encouraged by the local authorities: you can get 10 thousand rubles for 600 milliliters of plasma. In one of the following materials, we will describe in detail how to become a donor – to help other people and receive financial incentives for this.