Russia is in the top ten in terms of the number of people vaccinated against the coronavirus with the Sputnik V vaccine. People over 60 are in the priority group. How immunity changes with age and why it is important to be vaccinated against COVID-19? The director of the I.I.Mechnikov Research Institute of Vaccines and Serums, Doctor of Medical Sciences, Corresponding Member of the Russian Academy of Sciences Oksana Svitich told.
– what happens to the immune system over the years? Aging like the whole body?
– From birth to old age, our immunity undergoes many changes. Children and young people have many naive T and B lymphocytes. They are ready to perceive a new antigen (a component of an infection that the body recognizes as an enemy. – Ed.), To react to it, to form a full-fledged memory that will provide specific protection for a long time. With age, the number of memory cells increases, this is the experience of contacts with infections and vaccines, and the pool of naive cells that are the first to meet unknown pathogens decreases. Therefore, it is more difficult for the elderly to face new challenges.
– So, the older you are, the better your adaptive immunity?
– He is specific, he remembers what the person had been ill with and took root in childhood and young age. For example, new strains of influenza emerge every year. The body has not encountered them, there is no immunity. It’s the same with the coronavirus. SARS-CoV-2 is dangerous in that it leads to an immunodeficiency state. The risk of opportunistic infections, neoplastic and other serious diseases increases. Even a relatively harmless infection with COVID-19 can cause serious complications. The elderly often have cardiovascular ailments and metabolic disorders. This plus immunodeficiency after an infection does not have the best effect on health. We see that mortality in the over 60 group is more associated with complications than directly with COVID-19. It’s easier for the young.
– Now people of the older generation have access to the Sputnik V vector vaccine. What processes in the body is triggered by this vaccination?
– Sputnik V this is a vector-based vaccine – adenovirus. In this case, he plays the role of a carrier. This platform is used to present the coronavirus spike protein to our immune system. It triggers cascades of reactions, which ultimately should lead to the development of specific protection in response to this protein. These technologies are aimed at generating antibodies, in particular neutralizing antibodies, against various components of the coronavirus, as well as activating cellular immunity.
– Are antibodies to adenovirus also produced?
– The vector contains components of the adenovirus, and there can be a reaction to them. Therefore, the same vector is not reintroduced. Sputnik V has two different adenoviruses. First, an injection is given with one, then with the second.
– If the temperature rises after vaccination Sputnik V, then the vaccine worked?
– High temperature is the body’s reaction to the drug. There is no direct correlation with the effectiveness of the vaccine. For some, their pulse quickens only from the fact that they are in the office with a doctor in a white coat. And for people with a number of pathologies, vaccination may not work at all.
To find out if the Sputnik V is effective, it is necessary to test the humoral and cellular immunity. If no antibodies are detected, there is no immunity. It happens that antibodies did not have time to develop. Or only cellular immunity has formed. It is determined by special test systems, of which there are not so many yet. They are in development and are likely to become as routine as ELISA tests for antibody detection in the future.
If there is no cellular immunity, then the vaccine may not have worked. Then either re-vaccination with this or another drug, or the use of other means of protection, is recommended. They react to the vaccine in different ways. With this infection, not all processes fit into the classical concept of antiviral immunity.
– Are vaccines effective against new strains of coronavirus?
– In new strains or variants of the coronavirus – single changes in the genome sequence, for example, because of them, the virus can otherwise bind to the receptor to enter the cell. When the target antigen – the spike protein for many modern drugs or another antigen – changes a lot, vaccination will not protect against it. It’s like the flu. New strains are constantly emerging and new vaccines are required.
Perhaps the coronavirus is “adapting” to our population and the target antigen will not be greatly affected by the changes. If the rate of mutation increases, new strains will appear.
– If a person is vaccinated against influenza and pneumococcus, will this protect against coronavirus?
– The antigens are not similar, so you should not expect immunity from all infections. In the literature, there are data that antigens cause activation of the mechanisms of innate immunity and, as a consequence, cross-reactions to a non-target antigen. But when this happens, it remains to be studied.
– Vaccinations are in full swing all over the world. When will the incidence of COVID-19 decrease?
– For this, it is necessary that eighty percent of the population contacts the components of the coronavirus through vaccination or infection. Otherwise, one cannot talk about herd immunity.
– What vaccine is better for people over 60 years old? Vector, peptide or killed?
– In classical vaccinology, children and young people are vaccinated. The elderly are considered a risk group that is not vaccinated. The exception is flu and, now, coronavirus. This is a new infection for us, immune responses are not described in textbooks. For example, antibodies that quickly disappear after an illness is not a completely understood phenomenon, probably associated with the peculiarity of the formation of memory cells. The incompletely studied cellular mechanisms of adaptive immunity are of interest from the point of view of both fundamental and clinical immunology. It is essential that the virus, through non-structural proteins, suppresses the interferon link of immunity. There are a lot of questions to which there are no answers yet.
However, in anticipation of herd immunity from contact with coronavirus infection, there is a risk of losing some patients from risk groups, so they are vaccinated.
For the elderly, the safety of the drug is primarily important, because they have many chronic diseases and immune mechanisms work differently. And, of course, efficiency is important. Genetically engineered and peptide vaccines have minimal side effects. Every day we are faced with a huge amount of proteins, this is usual for the immune system. But the effectiveness is higher in vaccines that contain more components of the virus, and better – a weakened version of the virus. Many different antibodies are produced on them at once, and the immune system reacts actively. An attenuated (attenuated) vaccine is considered the most effective. It causes an infectious process “in miniature”. But these options are not safe for at-risk groups.
Personalized prophylaxis, when each risk group is vaccinated according to its own scheme, could decide for whom which drug to use. We take different vaccines and compare which option is better for the older age group, which one is for other categories. Then many questions would have been removed.
– Tell us about the developments of your institute that will help fight COVID-19.
– We create drugs for the emergency prevention of viral respiratory infections, in particular coronavirus. Such funds are needed by doctors working in the “red zones”, the elderly, who have to be in the office, metro and other public places.
One of our developments is a drug for modulating the mechanisms of innate immunity, it creates the phenomenon of “trained immunity”. The point is to stimulate the body with bacterial components, and as a result, a nonspecific defense against a number of other infections, in particular respiratory viruses, is formed. Initially, the drug was intended for children, now we are preparing a version in the form of a spray. They are better off protecting the upper respiratory tract – the gateway for many infections. At our institute, older employees use this medicine. Thanks to him, they are protected from infections for several months.
The second approach, which we are implementing together with the IOGEN RAS and the ICBFM SB RAS, is a temporary blocking of the expression of cellular genes through RNA interference. It’s about changing the metabolism of those cells that are involved in the reproduction of the virus. If cell transport and other processes are blocked for some time, then the virus, even if it enters the cell, will not multiply. It will simply remain in the cage until it naturally collapses. By doing this, we reduce the viral load in the body. Such a preparation in the form of a spray can be used as an emergency prophylaxis. In combination with other means, it will be possible to achieve maximum safety for various groups of the population.