CoViD 19 vaccines are now available at the vaccination centres as a part government’s massive vaccination drive. They have been reported to be safe and effective against the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) or coronavirus.
How does coronavirus look like?
It is helpful to know how the coronavirus looks like to understand how it infects the host and how CoViD 19 vaccines work. The coronavirus contains RNA genome packed inside an envelope with some proteins. The envelope has got spike proteins all over the surface of the coronavirus.
How does our body recognize the coronavirus?
The coronavirus enters our body through nose and mouth, into the respiratory pathway. They stick to the surface of air sacs, called alveoli, inside the lungs using the spike proteins.
Consequently, when our immune system finds the spike protein it knows that the virus has entered our body. It activates the host immune response to get rid of the coronavirus. Depending upon how strong ones’ immune system is the infection takes 2-14 days to show symptoms.
What is host immune response?
When bacteria or viruses or anything from outside the body (dust, pollen, etc.) enters inside our body, our immune system senses the attack. As a result, starts a series of processes called the host immune response in order to deal with the attack. Luckily, our immune system is very versatile and quick enough to save us on time.
After every infection our body makes memory B-cells and T-cells. That’s how it remembers how to fight against infection faster when it happens the next time.
How CoViD 19 vaccine fights against coronavirus infection?
Coronavirus enters human body and makes more coronaviruses that makes us sick. This process is scientifically called infection stage.
Our immune system thinks CoViD 19 vaccine is coronavirus because they look similar. So, it starts the host immune response and makes the memory cells ready in our body. In other words, we don’t fall sick because the CoViD 19 vaccine is doesn’t make any coronavirus inside our body.
Types of CoViD 19 vaccines
CoViD 19 vaccines are of different types based on what they are made of. That’s how and why different coronavirus vaccines work in different ways:
- mRNA based CoViD 19 vaccines
- protein subunit based CoViD 19 vaccines
- vector-based CoViD 19 vaccines
Mechanism of action of the CoViD 19 vaccines
1. mRNA based CoViD 19 vaccines
The genome of coronavirus is made of RNA (ribonucleic acid) which contains all information for making all the parts of coronavirus. The mRNA-based CoViD 19 vaccines contain mRNA (messenger RNA). This mRNA is a part of the genomic RNA that produces the spike proteins.
The mRNA produces the spike proteins that are found by immune system cells when injected into the bloodstream.
After that, when the immune cells find the spike proteins they start a host immune response thinking it as a coronavirus attack and create the army of memory cells to fight infection. The CoViD 19 vaccines made by Pfizer-BioNTech, Moderna are based on mRNA technology.
2. Protein subunit CoViD 19 vaccines
Just like the spike proteins, there are other proteins made by the coronavirus like membrane protein, envelope protein, etc. So, the protein subunit vaccine is basically a part of any viral protein that can generate a host immune response.
Once the protein reaches the bloodstream, the immune system recognizes the foreign protein and takes over. This leads to the production of memory cells that remember the same instructions to fight future infections. The example of protein subunit-based CoViD 19 vaccines are the ones from Novavax.
3. Vector-based CoViD 19 vaccines
The vector-based CoViD 19 vaccines work like the protein subunit vaccines. However, the only difference is that the protein subunit, which looks like the coronavirus protein, is packed within another non-harmful virus cover. This is done for efficient delivery of the CoViD 19 vaccines where they can trigger a better host immune response. Oxford-AstraZeneca COVID-19 vaccines are vector-based vaccines.
Dozes of the CoViD 19 vaccines
In other words, all the CoViD 19 vaccines basically mimic a part of the coronavirus that can start a host immune response in the human body without allowing infection. Once the immune response is generated the body remembers the memory of the infection and therefore, stays prepared for the next possible attack.
However, all the cells in our immune system die after a certain period of time and are replaced again by the immune system. So, we need to eat a healthy diet and stay fit so that the immune system stays active.
Some CoViD 19 vaccines are given in double dozes and some in a single dose for proper and long-lasting host immune responses. The formation of immune cells and memory B-cells and T-cells takes time and energy.
For example, when the first dose is taken, it starts the host immune response that creates a small working army of immune system cells. The second dose boosts the first doze army to create more soldiers to be ready to fight potential coronavirus infections.
Symptoms
There are a variety of symptoms or signs seen among the coronavirus vaccinated patients so far. The symptoms show up because our immune system has found the CoViD 19 vaccines and has started producing immune system cells. The common symptoms are similar to that of coronavirus infection and include fever, cold, headache, breathlessness, etc.
Summary
In conclusion, the CoViD 19 vaccines are biological preparations that mimic the properties of coronaviruses. It starts a host immune response against the coronavirus leading to formation of memory cells inside our body. That’s how the CoViD 19 vaccines prepare our immune system to fight without letting us fall sick. This way when the coronavirus attacks us, our body already knows how to deal with it and infection is blocked.