Ever since novel COVID-19 began infecting the masses, scientists and health professionals have been trying to find a way to combat it. The virus has crossed the toll of 80 million infections globally, but a few vaccines are very close to making the cut and getting final approval from health authorities worldwide. A few of them are currently in the final stages of trial phases, but various governments have already placed orders for billions of doses. But how exactly do these vaccines work? And how will they offer resistance against COVID-19?

How our immune system fights diseases

First, let’s examine how our immune system fights illnesses. Once germs, like the virus that leads to COVID-19, enter our bodies, they attack and begin to multiply. This is called an infection, and what makes an individual sick. This is where our immune system comes into action. It pulls many gears to contest against the infection and fight it.

The red cells in our blood help transfer oxygen to the organs and tissues present in our bodies. The white cells or ‘immune’ cells in our blood fight the infection. Our body has three kinds of white blood cells present, which fight infections in numerous ways. Below are the different types of white blood cells present in our body:


T-lymphocytes are a kind of white blood cells, and they attack infected cells present in the body. When an individual is infected with the virus that causes COVID-19, their body takes many days or even weeks to produce and use all the necessary tools to recover from the infection. Once the person fully recovers, their immune system remembers what is learned from the experience and how to safeguard the body against that particular disease.

The body has T-lymphocytes, also called ‘memory cells,’ which are again called into action if the same virus enters the body again. However, professionals are currently learning how long T-lymphocytes protect a person against the virus that leads to COVID-19.


These are white blood cells that swallow or digest dead or dying cells and germs. Fragments of the invading germs called antigens are left behind by the macrophages. The body then takes notice of the antigens and produces antibodies to attack them.


They are defensive white blood cells that produce antibodies, which attack the remains of the virus left behind by the macrophages. When familiar pathogens are detected, B-lymphocytes make antibodies to counter them.

How does a vaccine work?

Vaccines provide immunity from other germs or viruses by stimulating the body’s natural defenses to strengthen the immune system. The immune system then produces antibodies that help fight the germ, which helps prevent the person from getting sick. Then, if the body comes across that germ again, the immune system recognises it and knows how to battle against it.

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How will a COVID-19 vaccine work?

Any COVID-19 vaccine will generally allow our body to develop immunity to the virus without us having to get sick. There are different types of vaccines, all of which work in different ways to offer protection. The goal with all kinds of vaccines is that the body has an ample amount of B-lymphocytes and T-lymphocytes that will know how to fight that virus if ever reencountered in the future.

Usually, it takes your body a few weeks to produce T-lymphocytes and B-lymphocytes after getting a vaccine shot. So it is likely that a person could still be infected with the virus before or right after the vaccination.

Sometimes you might also experience symptoms like fever after vaccination. If you feel such symptoms, they are normal and a sign that the body is building immunity. However, you should always contact a qualified health professional immediately if you notice any side-effects.

What vaccines are currently present for COVID-19?

Below are the approved vaccines, that have at least one trial phase completed as of December 2020. At the moment, there are three primary types of COVID-19 vaccines that are, or will, be undertaking large-scale or phase 3 clinical trials.

Messenger RNA (mRNA)

This type of vaccine contains material from the virus that causes COVID-19; this helps in giving our cells the directions on how to produce a protein that is less harmful protein, which is exclusive to the virus.

Once our cells make copies of the protein, the genetic material from the vaccine is demolished. Our body realizes that the protein shouldn’t be there. So, T-lymphocytes and B-lymphocytes are produced that will remember how to fight the virus if we are infected in the future.

Vector vaccines

They have a weakened version of a live virus, which is different than the one that causes COVID-19, which has genetic material from the same virus that causes COVID-19 injected in it. This is called a ‘viral vector.’

When the viral vector enters our cells, the genetic material gives directions to produce a protein that is unique to the virus. Our cells then make copies of that protein, and in conclusion, T-lymphocytes and B-lymphocytes are produced. The two cells then remember how to fight the virus if encountered in the future.

Protein subunit vaccines

Protein subunit vaccines contain harmless pieces of the virus rather than an entire germ. When vaccinated, our immune system recognizes that the protein is foreign and starts producing antibodies and T-lymphocytes. If again encountered in the future, memory cells will fight the virus.

How COVID-19 mRNA vaccines aim to protect against the virus

Our cells are given the instruction to make a harmless piece of ‘spike protein’ through mRNA vaccine. It is found on the surface of that virus that leads to COVID-19.

The vaccines are injected into the upper arm muscle. When the instructions are inside the immune cells, a protein piece is made. From there onwards, the cell breaks down the instructions and discards them.

The cell displays the protein piece on its surface. When our immune system observes that the protein is foreign and doesn’t belong there, it begins to build an immune response by producing antibodies. In the end, our bodies learn how to protect against similar infections in the future. The benefit of mRNA vaccines is that when vaccinated, an individual gets this protection without getting sick with COVID-19.

What you should do if you don’t have access to the vaccine

If you do not have access to the vaccine currently, simply follow the guidelines put in place by the government. Use a mask to cover your mouth and nose, do not come in close physical contact with those who are ill, and keep at least a 2-meter distance from others. In terms of hygiene, wash your hands frequently using the proper technique, and avoid going into crowds if you don’t need to.