From February 21, Russians can receive certificates of a coronavirus infection based on an antibody test. And this will greatly help not only themselves (they will be able to visit places where a QR code is required), but also Russian healthcare in general, as well as science.
Issuing certificates based on an antibody test will allow us to more accurately determine the level of herd immunity in a country. After all, they can only form in a vaccinated person, or someone who has been in contact with the virus. And since a lot of people were asymptomatic or were not tested at the time of illness (that is, the diagnosis was not confirmed by tests), the healthcare system “did not see” them.
Antibodies for coronavirus can be different. Protective are those that are formed on the spike or spike protein of the coronavirus. There are also antibodies against other components of the virus – if a person has met with an infection, and not with a vaccine. In an unvaccinated person, even a low antibody titer indicates that he met with a viral infection. It is very important to understand how many such people are. We officially register those who have been vaccinated, those who have been ill, who went to the doctor and were tested, too, but we do not have correct data on those who met with the infection in an asymptomatic form or were ill without tests.
It is necessary to observe the statistics, to obtain information on how often people who have antibodies become infected. Thanks to this, we could draw some conclusions regarding the possibility and frequency of infection of different groups – both those who have been ill, and those who have been vaccinated, and those who have not been vaccinated. These indicators can give us population statistics on both the effectiveness of vaccines and the effectiveness of immunity in the case of a previous infectious process.
Population immunity is reflected by seroprevalence – this is an indicator that determines the possibility of the formation of new waves of a pandemic, that is, new cases of severe infections and cases of hospitalization and death. This allows us to predict what will happen next.
From a personal protection point of view, a vaccination certificate is not the same as an antibody certificate. Coronavirus strains are quite different, and the formed natural immunity after meeting with the coronavirus, especially asymptomatic ones, is prone to breakthrough infection due to virus mutations. Those who are vaccinated are better protected. Such people, unambiguously, are much less likely to get seriously ill or die than those who had the infection a year ago, for example. And the strongest immunity is formed in those people who have had a coronavirus infection and then vaccinated.
Alas, antibodies to coronavirus and spike protein are not stable enough and do not persist throughout life, unlike antibodies to a number of other past infections or vaccinations. Therefore, their definition is also required to understand whether a person still has any protection or whether it has already disappeared. Despite the fact that cases of re-infection occur both in those who were sick and in those who were vaccinated, the proportion of “second hits” in both groups is much less than the incidence among those who do not have any antibodies at all.
You can look at countries where vaccination rates are very high, such as Israel. There, the arrival of the Omicron strain was characterized by a high incidence, but there were only a few severe cases and deaths. Unlike Russia, population immunity in this country is formed for the most part by vaccination.
However, there is still no standard by which we can be guided and say that a certain number of international units of antibody titers completely protects against infection. The only thing we can manage in a pandemic is our vaccination status and anti-epidemic measures.
The author is an associate professor of the Department of Infectious Diseases in Children of the Russian National Research Medical University. Pirogova, infectious disease specialist
The position of the editors may not coincide with the opinion of the author
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