What are the differences in the immune system’s response to vaccination in people who have previously had COVID-19 or have been confirmed to be infected with SARS-CoV-2 and those who have not? Is one dose of the vaccine enough for convalescents?
COVID-19: Healers’ Resilience
IgM (immunoglobulin M) antibodies are antibodies produced when humans first come into contact with an infectious agent. They are the body’s early response to an infection. In contrast, IgG antibodies are revealed later in the course of infection and are part of immune memory. These immunoglobulins play a protective role in many infections against reinfection.
In most infections, increased levels of IgG antibodies correlate with increased resistance to the pathogen against which the immunoglobulins are directed. This phenomenon is currently used in the case of preventive vaccinations.
Together, these immunoglobulins reflect the body’s humoral response (a set of various activities that our body performs when there is a real threat of disease) to contact with a pathogen or simulated contact in the form of vaccination.
Research into the role of antibodies in fighting SARS-CoV-2 infection is currently underway, but due to the high degree of similarity among coronaviruses, many research projects are relying on the COVID-19 analogy to other infections caused by SARS-CoV or MERS-CoV. On this basis, we can assume that antibodies generated as a result of the primary infection may play a protective role in the event of reinfection. A higher ability of the immune system to synthesize specific IgG antibodies as a result of contact with the virus after prior vaccination has also been noted. It is suspected that a high number of antibodies in the body may prevent infection, and a lower number may reduce the risk of a severe course – explains Agnieszka Staniszewska from the INVICTA Research and Development Center, where research is currently being conducted on the level of mature IgG and IgM antibodies against SARS_CoV-2 after vaccination. against COVID-19 by Pfizer-BioNTech (Comirnaty).
Vaccinations against COVID-19 in convalescents
The results obtained so far clearly show the difference in the immune system response to vaccination in people who previously had COVID-19 or had confirmed infection with the SARS-CoV-2 virus, and in those who did not. In the group with no history of coronavirus infection, the average level of antibodies within 14 days from the first dose of the vaccine was on average 60,99 U / ml, and just before the second dose of the vaccine (i.e. usually after about 21 days from the first dose), it increased to an average of 122,83 U / ml.
People who were infected with SARS-CoV-2 before vaccination, already before vaccination, obtain results at the average level of 54,94 U / ml, and 14 days after the first dose, their antibody level exceeded 2 U / ml (500% of respondents) .
The first group (no history of infection) needed a second dose of the vaccine to achieve this antibody level. Among these people, 71 percent. has reached antibody levels above 2500 U / ml on day 8 after the second dose of vaccine.
On the one hand, the obtained results allow us to suspect that perhaps in people who were infected with SARS-CoV-2, one dose of the vaccine is enough to achieve an effect analogous to that in people without prior contact after two doses. They also ask the question to what extent the level of antibodies alone is a determinant of persistent immunity. Since, after the first dose, the body of an infected person is able to produce several thousand units of antibodies per ml more than that of a person without prior exposure, this means that in addition to the number of antibodies in the bloodstream, the body’s ability to produce them is also important.
– On the other hand, the number of antibodies remaining after contact does not seem to have a decisive influence on this ability, because no matter how many units of antibodies were recorded before the first dose of vaccination in a person who had become infected, almost all of our previous participants in the “post-illness” group exceeded test range, i.e. 2 500 U / ml. This may suggest that not only the presence of the antibodies themselves is involved, but also the so-called immune memory cells, and this may mean that immunity to the virus may persist even after antibodies are eliminated from the bloodstream, because the body will “remember” how to produce them, explains A. Staniszewska.
– It is also worth mentioning the so far unexplained individual cases among study participants whose bodies seem to respond to vaccination to a very limited extent. From the group of people studied so far, eight people, even after the second dose of the vaccine, did not have antibody levels above 1000 U / ml, and two did not exceed 100 U / ml – adds A. Staniszewska.
The causes of this phenomenon are unknown in relation to these specific participants (there are known in the literature cases of a weakened immune response associated with certain chronic diseases, pharmacotherapy of these rtc diseases.) And although the level of antibodies does not appear to be directly related to the “degree of immunity” to the SARS virus -CoV-2, this however, people with such a weaker immune response should exercise extreme caution.
It is always a good idea to do blood tests after recovery from COVID-19 to check your health status.
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