In the context of the global COVID-19 pandemic more than 3 Billion people worldwide have already been vaccinated and medical topics become more and more popular since they affect all of our lives. Vaccinations serve as a precaution measurement against infectious diseases by “training” our immune system in order to be prepared for the actual germs without us having to get the disease.
The following article explains the processes that occur in our bodies after being vaccinated and how they lead to immune protection. In case of the mRNA vaccination a mixture of mRNA, lipids, sucrose and chlorides is injected intramuscularly. The mRNA codes the information for the characteristic Spike protein of Covid-19 which is located on the surface of the virus and can thus be considered an easy target for our immune cells. A cover of lipid and sucrose that is wrapped around every mRNA ensures that these molecules arrive at our cells without being decomposed. After entering a body cell the mRNA strand bounds to the ribosom where amino acids are being linked until the Spike protein is complete. It is important to note that this process is similar to the natural protein synthesis in our cells. Since the Spike protein is a foreign molecule in our body it triggers the adaptive immune system. On the one hand there is the humoral immune response in our blood as well as in the lymph which is carried out by B cells. B cells present antibodies on their surface that possess a great variety of molecular structures. The spike protein now binds to B cells with fitting antibodies which leads to the activation of this specific B cell. This cell now divides into plasma cells that release millions of copies of the antibody on the original B cell. Those antibodies bind to the viral spike protein and consequently mark them to be destructed by makrophages and a protein system. On the other hand there is the cellular immune response carried out by T cells that targets infected tissue cells.
Furthermore the activated B cells differentiate to B memory cells that can endure for several years and memorise the information of the Covid-19 spike protein. This immune memory is the foundation of the functioning of vaccinations. For when a vaccinated human is being infected with the actual Covid-19 virus the secondary immune response is triggered thanks to the memory cells. Said secondary immune response is significantly faster and more efficient than the primary immune response which enables our body to extinguish the virus before we get the symptoms of the sickness. The duration of the immune protection through vaccination alternates depending on the disease. For instance the measles vaccine ,that has first been introduced in 1963, offers lifelong protection. However it is not yet certain how long the immune protection from Covid-19 vaccines will last since this disease is a rather recent phenomena. Today the majority of scientists agree that after 4-6 months at least patients with higher risk should receive a booster vaccination in order to maintain the full protection.
Sources:
https://en.wikipedia.org/wiki/Immune_system
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html