Although the vaccine development process is a difficult and long process, the vaccines that were developed and started to be used in a very short time in order to combat the Covid-19 epidemic brought with them question marks. The long-term consequences are still unknown, but the ever high prevention and reduction in mortality; promising in terms of changing the course of the epidemic.
So, what is a vaccine?
When pathogenic microorganisms enter our body, they are identified as foreign particles and create an immune response. The main purpose of the immune response is to destroy these foreign particles it sees. Foreign substances (antigens) stimulate the immune system and specific antibodies are formed that help them to be destroyed. The common logic in vaccines is to introduce this microorganism to the body before encountering the pathogenic microorganism, to create an immune response in the body and to reduce the risk of infection by keeping the body's defense system ready in a possible encounter.
If we examine the vaccines currently in use;
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Sinovac Vaccine; It is an inactivated vaccine. In other words, the disease-causing properties of virus particles have been eliminated. When it is given to the body in this way, it creates the immune response that the normal virus creates in the body, but the disease does not occur and the virus does not multiply in the body. According to the data of the Ministry of Health of the Republic of Turkey, the results of the phase III study determined the effectiveness of the vaccine as 91.25%.
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Sputnik V and AstraZeneca Vaccines; Viral vector vaccines. Vector is the name given to the mediator virus that is used to introduce the desired material into the body. Using molecular methods, the part of the genetic material of the SARS-Cov-2 virus related to the S protein is transferred to another virus (adenovirus) whose disease-causing potential has been eliminated. When this vector virus enters the body, it begins to produce S protein in certain cells. Thus, the immune system is triggered and antibodies against this S protein begin to be produced.
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Biontech/Pfizer and Moderna Vaccines; mRNA vaccines. The mRNA vaccine technology, which was used for the first time with the covid-19 epidemic, has actually been researched for various diseases for a long time. In general, mRNA receives the necessary information for protein synthesis from DNA and transmits it to the ribosome (protein synthesis organelle). In other words, the code that will become a protein is hidden in mRNA. In mRNA vaccines, this hidden code is the code for the S proteins of SARS-Cov 19. The mRNA with this code is trapped in an oil droplet, thus facilitating its entry into the cell. In the ribosome of the cell, mRNA is read and S proteins are synthesized, thus stimulating the immune system.
The S proteins, which are formed as a result of mRNA and viral vector vaccines, are the crown-shaped proteins that give the virus its name. The production of these proteins in the body cells does not cause any infection, they do not have any disease-causing effects on their own, they only provide the formation of antibodies against themselves.
Although the declared efficacy results of these vaccines in use are promising with a protection of 50% and above, there is no clear information yet about how long their protection will be. The strength of the immune response created by vaccines cannot be expected to be the same in every person because the immune system is a complex system that is affected by many factors such as age, psychology, and other underlying diseases.
In order for the expected effect from the vaccines to be maximum, both doses must be taken. A second dose is given some time after the first dose to increase the number of antibodies. Some experts state that the number of antibodies may decrease with time and a third dose may be required. It is recommended to continue to follow the mask and distance rules for now, as the answer to the question of whether the vaccinated people can transmit the virus or not, is still unclear.
