Let me start off by saying that I am not an anti-vaxxer, quite the contrary. But there are different vaccines, especially now against a well-known virus. So what do we have for today?
Gamaleevsky Sputnik V. A sensational and very modern vaccine, only pure gene therapy is ahead. It is not surprising that so much effort, time and money have been invested here. It is still the only one possible in our country. Its obvious advantages: maximum immune response (in addition to antibodies, we have cellular immunity) with minimal side effects. But there is a nuance about which, for some reason, if they talk about it, then very, very little, and of course not in the media, but in specialized medical publics. Now I'll explain what I'm talking about.
This vaccine is a genetically modified adenovirus, or rather two neutralized adenoviruses (5th and 26th serotypes), which are introduced into the body with an interval of 3 weeks. The gene for the spike protein of the coronavirus is embedded in the genome of each. In fact, these are “cars” whose task is to deliver an important “passenger” to its destination. And then everything goes as nature intended: the adenovirus delivers the coronavirus gene to the cells, unpacks there and begins to produce proteins of both the “passenger” and its own. Pieces of these proteins are exposed by the infected cell, thereby teaching t-lymphocytes. After the destruction of the "factory cell", viral proteins (namely proteins, and not virions ready to infect new cells, as in a disease) enter the bloodstream, thereby stimulating the production of antibodies. It is impossible to get sick, immunity is being formed, and everything seems to be fine. But a side effect of this vaccine is the development of an immune response to the adenoviral components of the vector themselves. As a result of the repeated introduction, the “car with a passenger” simply will not have time to reach the cell, but will be immediately destroyed by the antibodies that are formed as a result of the previous “acquaintance”. It turns out that Satellite V can only be used once. And this is fraught not even so much with the fact that the vaccine can no longer be used for its intended purpose - the intensity of immunity to the coronavirus is still unknown to anyone, and there seem to be cases of re-infection, but few. The lifelong restriction on any potential adenovector gene therapy, including the treatment of oncology, which may be needed in the future, is frightening. All this is now actively developing, and after such a “large-scale testing”, things will go even faster. But then again, this therapy may or may not be useful, and immunity to the virus is needed today. Therefore, here everyone chooses for himself what is more important to him. The vaccine turned out to be quite normal, for the elderly - that's it. But in the place of the young (after all, they have every chance to use gene therapy in the future), I would think about it.
I heard about the development of a version of Sputnik-Light, for those who protect (figure) immunity. It will be a one-component vaccine based on only one serotype. This option is nicer, but it's not scheduled to be released until December 2021.
Two more Russian vaccines: EpiVacCorona of the Vector Center (produced on the basis of viral proteins) and the whole-virion Chumakov Center (made on the basis of a whole virus) are already on the way. Both are made in the old fashioned way. There is an opinion that it is for this reason that they are doomed to failure, and also because they do not activate t-cell immunity, which is not cool now. Now a little about each, since a lot about them is still not known. Apparently, their PR is so-so, or maybe it's just a military secret.
Chumakov's whole-virion vaccine is a classic, humanity has grown on such. A whole virus is used here, which forms a reliable immunity, as it gives a complete set of antigens. But the virus is dead, so the immune response will be only antibody, but powerful, and the reactions are strong. Harsh, but during the epidemic, it is suitable, especially for the healthy, desperate and courageous. Of all the wealth of choice, I would prefer it because of the understandable mechanism for the formation of immunity. But she's still only in her mind. She doesn't have a name yet. But large-scale production is planned in March. Wait and see.
The third Russian vaccine is EpiVacCorona of the Vector Center. It does not contain the biological component of the virus from the word at all, but only its synthesized proteins, so as not to force our cells to work and strain at all. The vaccine is mild, without side effects, but also without good immunogenicity. So far, peptide vaccines that produce long-term, stable immunity have not been invented. Therefore, in order to enhance the immune response, they use adjuvants. Here is aluminum hydroxide. Whether this is good or bad, I don’t know, but it is believed that the fewer “ingredients” in the vaccine, the better. But with the Vector vaccine, unlike Sputnik V, it will be possible to vaccinate an infinite amount. And it was also tested on the elderly (65+) and children (14-17), as well as on people with chronic diseases. They're trying to share the pie. As for the children, I agree, but as for the elderly, I'm not sure. They now urgently need RELIABLE protection. The vaccine was supposed to go on sale at the beginning of the year. I wonder if it's already there somewhere?
Well, the main foreign vaccines, where without them. Produced on the basis of adenovector technologies: Chinese CanSino Biological. Made on the 5th adenovirus serotype, which is widely distributed in the population. It is believed that 30% of people are already immune to it, so the vaccine for them will not be very effective. American Johnson&Johnson - based on serotype 26. This strain is less common, but it's still a possibility. Therefore, Sputnik took both platforms at once, to be sure! British-Swedish vaccine AstraZeneca/oxford. At the moment - the most ordered in the world. About 3 billion doses have already been ordered. It is derived from the chimpanzee adenovirus. This, of course, gives a 100% guarantee that the human immune system has not encountered such a virus before and will not encounter it afterwards, but if a zoovirus mutates, it can give unexpected results in the human body, which in itself is somehow alarming.
Based on mRNA technologies, two world forwards have been made: Pfizer BioNTech and Moderna. This is a completely new direction, which at the moment is simply the pinnacle of pharmacology. Until then, no mRNA vaccine had yet existed. The technology is somewhat similar to vector, but different. There is no third-party viral component here, and an artificially created lipid nanoparticle is used as a “machine”, which easily penetrates the membranes of our cells, and the “passenger” is the same gene or mRNA encoding the coronavirus spike protein. At the same time, the cells into which the mRNA enters are not destroyed, and the protein simply quietly comes out, forming a good t-cell and antibody immunity. Everything seems to be fine, but again there are nuances. Firstly, it is polyethylene glycol, which is used to stabilize mRNA along with low temperatures (down to -70), which in itself is an allergen and can cause severe reactions, up to anaphylactic shock. And secondly, these are the most unexpected destinations of our “passenger”. And if the natural target of adenovirus is specific cells, often cells of the upper respiratory tract, where the coronavirus gene is delivered in adenovector vaccines, then only God knows where the coronavirus mRNA will be delivered by lipid nanoparticles. And these can be completely different places where they will also have to work: blood vessels, joints, nerves, etc. Side effects are already known in the form of various autoimmune processes, temporary paralysis, etc. You don’t have to go far, the entire Internet is full of side effects from Pfizer. But the vaccine is not withdrawn from use. So what if you look a little with a twisted face? This is not comparable to the most severe course of covid, right? On the other hand, antibodies to this “car” are not produced, but only to the “passenger”. In general, there is something to think about.
Based on recombinant proteins, the American vaccine Novavax was made. The vaccine is second in the world in terms of the number of doses booked. So what is her secret? And in some unique technology of “assembling” recombinant proteins into nanoparticles, due to which the immunogenicity of the protein is increased, and also in the original Matrix-M adjuvant. Well, that's all for now.
Sinovac is another Chinese-made vaccine. It is whole-virion, which is the reason for its popularity. Usual storage conditions and a clear mechanism for the formation of immunity could make it available in many countries. According to the results of the first two phases of the trial, it was considered one of the most promising, but on the intermediate results of the third phase, the vaccine showed an effectiveness of only 50%. I wonder if this can be trusted?
Somehow like this. One thing is clear that there is no perfect vaccine in the world right now, but some decision will have to be made sooner or later anyway. In any case, I wish you all health and strong immunity!
Source: habr.com