Sputnik in Argentina
What did Argentine scientists actually find out when testing the effectiveness of Sputnik V?
The Russian vaccine Sputnik V against the SARS-CoV-2 coronavirus was registered in Argentina back in December 2020. Recently, Argentine researchers published results to assess its effectiveness six months after vaccination on healthy volunteers and people who had previously suffered the disease.
According to WHO, by August 2021, the COVID-19 pandemic had claimed more than 4.4 million lives. Today, it is believed that the main way to stop the pandemic (or at least reduce the number of severe cases of illness and deaths) is mass vaccination.
Although there is a problem here – the emergence of new viral variants with mutations in the gene encoding the surface protein-spike S, with which the coronavirus infects the cell. Such viral strains can potentially "escape" from the action of neutralizing antibodies produced as a result of the action of vaccines created to counteract the progenitor strain.
As you know, Sputnik V, developed by the N. F. Gamalei National Research Center for Epidemiology and Microbiology (Moscow), is based on a genetically modified adenovirus with a coronavirus gene encoding a spike protein embedded in its genome. And recently, Argentine scientists published a preprint (the so–called "raw" version of the article), where they assessed the level and neutralizing ability of IgG antibodies against this coronavirus protein in 118 medical volunteers vaccinated with two doses of Sputnik. It is believed that these antibodies, whose level usually reaches a peak in one and a half to two months after the disease, and then slowly decreases, and provide long-term immunity.
Lymphocytes synthesize five types of antibodies. Antibodies (immunoglobulins) are proteins with two "light" and two "heavy chains" connected by disulfide (S–S) bonds. The chains contain both constant and variable parts, which are responsible for the specific binding of antibodies to different antigens and differ significantly in different antibodies. Different types of antibodies differ in the structure and size of light and heavy chains, as well as in the presence of a J-component that binds several molecules to form dimers (IgA) or pentamers (IgM).
Blood samples from the subjects were taken before vaccination and 21, 42, 120 and 180 days after the first dose of the vaccine. Previously, the participants were divided into two groups according to the presence of appropriate antibodies even before vaccination – this indicator is considered as a marker of a transferred coronavirus infection. The activity of the obtained antibodies was evaluated in relation to both the original (Wuhan) variant of SARS-CoV-2 and the new ones: alpha from the UK, beta from South Africa, gamma from Brazil, delta from India and lambda from Argentina.
The first results were quite expected. It turned out that six months after vaccination, the level of IgG antibodies against the coronavirus spike protein in people who initially did not have them decreases by an order of magnitude. For those who had previously had COVID-19, this level decreased not so sharply, but at the same time the decrease came from higher initial values. As for the overall neutralizing activity of antibodies, it has also decreased somewhat over time. At the same time, the effectiveness in relation to the alpha and delta variants decreased slightly compared to the original strain, and to the beta and gamma variants – more noticeably.
Surprises were ahead. Having calculated the neutralization efficiency index (i.e. dividing the neutralizing titer of each sample by the concentration of IgG antibodies in it), the scientists found that the relative effectiveness of antibodies did not change significantly in those who had already been ill, but even increased in healthy vaccinated ones!
What do these results mean? Based on these data, it can be said that six months after vaccination with Sputnik V, the antibodies more effectively neutralized the SARS-CoV-2 virus, despite a decrease in their titers in the blood. So this last fact alone cannot serve as an indicator of the weakening of antiviral protection.
According to Argentine scientists, the relative effectiveness of neutralization of SARS-CoV-2 by antibodies increases as a result of their maturation process, in which the changeable areas of these immune proteins become better "adapted" to the target. And this will be true not only for the original "Wuhan" version, but also for others that appeared later.
As for the practical conclusions of this work, it testifies against the need to be vaccinated again in six months, which is what they are calling for today. This is especially important from the point of view of not only maintaining health, but also the availability of the vaccine, which is still not enough even for the primary "universal" vaccination of the population of the Russian Federation. And those who are thinking about the need for vaccination-revaccination from COVID-19 after an illness, can make a decision based on the analysis of the level of IgA antibodies in the blood. Usually such "early" antibodies disappear 3-4 months after the disease, but after all, "covid" is not like people!
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