COVID-19 VACCINE: HOW DO VACCINES WORK IN OUR BODY?

Germs are everywhere. They are all around us in the air, food, water, soil, and they are inside our bodies. Some of these microbes are harmful, and some are not. A microbe or an agent that causes infections and diseases is known as a pathogen. When these pathogens get inside our body, our immune system attacks and kills them. 

But our immunity is not always strong enough to fight off these pathogens. In the weakened state of our immune system, they can create serious problems. Sometimes they can even cause severe distress that leads to death. So in such cases, vaccination helps our immune system fight these pathogens.

COVID-19 is a pathogen that can cause symptoms like cold, cough, loss of sense of smell and taste, fever, and fatigue. It can also cause some severe symptoms like difficulty in breathing, respiratory failure, and shock. The symptoms are much severe in people who are already suffering from conditions like heart diseases and diabetes.  

Vaccination against coronavirus helps reduce the severity of these symptoms and controls its spread drastically. But first, we need to understand the basics of our immune system to know how these vaccines work.

What is the immune system, and what are the different components of it?

The immune system is made of a complex network of cells, tissues, organs, and proteins. All of them work together to protect the body against all infectious agents like viruses, bacteria, fungus, protozoa, and foreign bodies like dust and pollen. 

The following are the different components that are part of the immune system.

• Skin: The skin is the first layer of defence. It prevents the microbes from entering the body and keeps everything out.
• Mucous membrane: It is the membrane that lines all the body cavities and canals, such as the mouth, nose, stomach, and lungs. It produces a slimy substance, mucous, that traps all the foreign particles and prevents them from entering our bodies.
• Lymphatic system: A complex network of organs and cells that consists of lymph, lymphatic vessels, and lymphatic organs is the lymphatic system. It has three main functions
• Drain the various organs
• Transport fat from various places
• Help produce an immune response.
• White blood cells or WBCs: There are three types of white blood cells.

1. Macrophages: These WBCs eat and digest the microbes and foreign substances. They also present antigens to the T lymphocytes and help in killing them. They are not specific to any organism or pathogen.
2. B lymphocytes: They produce specific antibodies when antigens are presented to them. They are also called plasma cells. 
3. T lymphocytes: They kill the specific antigens presented to them.

How does our immune system work?

Our natural immune system defends and protects the body against substances that it considers harmful. Once the immune system recognizes them, it starts to attack and destroy these substances. This process is known as immune response. It produces antibodies as a part of this immune response. Any substance that can provoke an immune response is known as an antigen. Antibodies are a type of protein produced by white blood cells. The antibodies tag the antigens. The white blood cells then kill the antigens that are tagged by these antibodies.

How does our immune system respond to COVID-19?

Just like any other virus, when COVID-19 enters the body, our immune system works in its natural way to remove it. It recognizes and stimulates B cells to produce antibodies. These antibodies are specific to coronavirus. They tag the viruses and present them to other white blood cells to kill them. 

People whose immune system is not efficiently working do not produce these antibodies to fight off the virus. In them, the virus multiplies and spreads, leading to various symptoms.

COVID-19 can sometimes cause symptoms even in healthy people with good immunity. It is impossible to predict the effects of the virus in a person. So, vaccination for COVID-19 is important for everyone.

How do vaccines work in our bodies?

Vaccines are immunity boosters. They are prepared in the laboratory with biological variants of the entire pathogen or a part of it. They provide us immunity to fight that specific pathogen. A vaccine contains a particular agent that is similar to the pathogen. This agent is much weaker than the disease-causing microbe. So, when we are injected with a vaccine, the agent provokes an immune response without causing the disease or infection. It results in the release of antibodies against that particular agent. 
The white blood cells now have a ‘memory’ of these pathogens. So when we encounter that particular disease-causing pathogen in the future, antibodies are readily released without any delay. Therefore, vaccination reduces the risk of infection and the severity of symptoms. 

Vaccinations are generally given for two reasons–

• To prevent future infections from pathogens like COVID-19
• To treat infection or conditions that have already occurred, like cancer 

What are the types of vaccines?

Currently, for COVID-19, there are three types of vaccines being widely administered.

1. mRNA vaccines contain the part of COVID-19 that causes the infection. Once the body recognizes this, antibodies are produced by the immune system.
2. Vector vaccines contain a modified version of a different virus with a component of COVID-19 inside it. This type of agent is known as a viral vector. 
3. Protein subunit vaccines contain a small component of the COVID-19 instead of the entire virus. 

Is there a chance of getting infected after vaccination?

It usually takes a few weeks for the vaccine to work before producing antibodies. So, when we are exposed to the virus before our immune system has produced antibodies, there is an increased risk of infection. It is always recommended to follow all the necessary precautions for a few weeks after vaccination.

Can vaccines prevent COVID-19 from spreading?

Vaccination causes our immune system to develop resistance against the disease-causing antigen. Getting vaccinated before any exposure to the microbe makes it difficult for the antigen to flourish in the body, as the antibodies are already present. This prevents the COVID-19 virus from spreading to other people exposed to that person. 

What is the importance of a vaccine?

People with weak immune systems cannot get vaccinated, leaving them vulnerable to COVID-19. If everyone with a well-functioning immune system gets vaccinated, it becomes hard for the pathogen to spread. This is called herd immunity, where people who cannot be vaccinated stay protected.

What are the different COVID-19 vaccines available in India?

There are currently seven vaccines that are approved for use in India. All of them are made using different approaches and a variety of studies. Therefore, it is impossible to compare them. However, all the vaccinations approved by the WHO are efficient in preventing the severity of COVID-19.

The following are the three widely used vaccines in India.

• COVAXIN: Made using inactivated COVID antigen, the vaccine is made available in single-dose vials. It is recommended to use this vaccine in two doses. The interval between two doses should be four weeks. It is safe to use for everyone over 18 years of age.
   
• Covishield: The vaccine is made using a weakened common cold virus, adenovirus, along with a genetic component of coronavirus. It is also given in two doses at a recommended interval of four to six weeks. 
   
• Sputnik: This is a Russian-made vaccine that is approved but not being widely used in India. It is also given in two doses at the interval of 21 days.

How do you get the COVID-19 vaccine in India?

The government of India has set up a website, CoWIN, for booking vaccine appointments. Once you register on the website, the website shows all the available vaccination centers near you and available dates for vaccination. If you haven’t, get your vaccination for free today! 

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