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What is Sars-Cov-2?

The virus that causes Covid-19 is called Sars-Cov-2 virus.

How does Sars-Cov-2 virus enter the cell?

Sars Cov-2 virus binds to the ACE-2 receptors on the cell with the receptor binding domain of the spike protein, then enters the cell and begins to multiply. By blocking the region of the virus that binds to the ACE-2 receptor, the binding of the virus to the cells, and thus the entry of the virus into the cell can be prevented.profdromerdeniz.com

What is Coronavac (Sinovac) vaccine?

Coronavac (sinovac) is an inactivated virus vaccine. Sars-Cov-2 virus produced/replicated in Vero cells is condensed and purified after chemical inactivation with β-propiolactone, and then passed through a series of processes to become an inactivated vaccine. In the inactivated vaccine, there are other antigens of the virus as well as spike protein antigens. profdromerdeniz.com. Since there is no live virus in the inactivated vaccine, it does not cause a viral disease. After this vaccine is administered, mainly humoral immunity (immunity with antibody production) is formed against the antigens in the vaccine. There is little or no cellular immunity (absence of antibodies, predominant macrophage and T-cell immunity) against inactivated vaccines. profdromerdeniz.com

According to the results of the Phase1/2 clinical trial, it was reported that individuals who received the Coronovac vaccine had lower levels of antibody production compared to the antibody levels formed in individuals who had had Covid-19 disease. The protection of Coronavac against the Covid-19 infection caused by original Sars-Cov-2 virus (with no significant mutations) was reported between 50.7% and 84%. profdromerdeniz.com

What is Pfizer-BioNTech COVID-19 vaccine?

The Pfizer-BioNTech COVID-19 vaccine, an mRNA vaccine, carries the code for the receptor binding domain antigen of the spike protein of Sars Cov-2 virus. The vaccine can be described roughly as that it consists of modified mRNA that carries the code for the spike protein receptor binding domain antigen surrounded by lipid nanoparticles. profdromerdeniz.com. After vaccination, the vaccinated individual’s own cells produce the receptor binding site antigen of the spike protein of Sars Cov-2 virus. This antigen is not a virus, just a small part of the virus. Therefore, it does not cause a viral disease. However, since it is a foreign substance to the human body, both humoral immunity and cellular immunity are formed against this antigen. Since mRNA itself is also recognized as a pathogen by cells, it stimulates a strong immunity.

It has been reported that Pfizer-BioNTech COVID-19 vaccine prevents Covid-19 infection caused by the original Sars-Cov-2 virus (with no significant mutations)  by 95% in individuals aged 16 years and older who have not been infected with Sars-Cov-2 virus before.

Is the protection of Covid-19 vaccines permanent?

Immunity against Sars-Cov-2 virus in those who have had Covid-19 disease or who have been vaccinated decreases over time. Antibody levels against Sars-Cov-2 virus decrease as the time passes after getting sick or getting vaccinated. Furthermore, the Sars-Cov-2 virus is a frequently mutating virus. In other words, there may be changes in the antigenic properties of the virus. This situation reduces the protective effectiveness of antibodies caused by vaccine or disease. profdromerdeniz.com

Being immune or vaccinated against the virus due to the above-mentioned reasons may not prevent anyone from becoming Covid-19 again. Since the antibody levels formed in individuals vaccinated with inactivated virus vaccines are relatively much lower, the protection is greatly reduced or lost as the time elapses after the vaccine is administered. profdromerdeniz.com

The Pfizer-BioNTech COVID-19 vaccine continues to provide significant protection against mutated viruses, as it generates a very high rate of antibodies against the Sars-Cov-2 virus. However, it is observed that the protection against the Delta variant, which is still the most common variant in circulation, is considerably lower than the protection against the original Sars-Cov-2 virus (with no significant mutations) in individuals who have passed a long time after the second dose of vaccine. This is particularly evident in older individuals. profdromerdeniz.com