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Understanding the vaccination and its types

Fight against COVID-19: Understanding the vaccination and its types

 

The COVID-19 pandemic made the world realize the importance of preventive medicine and vaccination. Vaccines are one of the most effective ways to prevent serious infections and fatal diseases.

 

It became clear after the beginning of community spread that the only way to win from this situation is mass vaccination. It is a known fact that the creation, trial and testing take years for a vaccine. In this case, however, with the damages being fatal and worldwide, the speed of research and development had to be accelerated. 

 

The availability and equal access to safe and effective vaccines have been critical to ending the COVID-19 pandemic. Many vaccines were proving their potential and going into active production. WHO played a major role in providing valuable and trustworthy information about the effectiveness of the various vaccines available. WHO worked tirelessly with partners to test, develop, manufacture and deploy safe and effective vaccines. 

 

There are various vaccines that have been proven safe and effective for dealing with COVID-19. An effective vaccine is designed to protect the candidate who receives it by lowering the chance of getting COVID-19 if the person encounters the coronavirus. Vaccination helps prevent grave concerns related to COVID-19 such as serious illness, hospitalization and death. 

 

The coronavirus that causes COVID-19 has spikes of protein on each viral particle. The virus particles attach to the cells with the help of these spikes. This subsequently causes COVID-19.

 

Different types of COVID-19 vaccines 

Vaccines can be predominantly classified as per the preparation method of the antigen(s) which are used to generate an immune response against the disease-causing organism.

 

Vaccine platforms are designed to train the immune system of the human body. 

Two main approaches could be used to design the vaccine for COVID-19. The difference lies in whether they use a whole virus or bacterium; just the parts of the germ that triggers the immune system. 

 

This gives us two main categories--Whole Virus Vaccines and Component Viral Vaccines.

 

(A) Whole Virus Vaccines

 

The oldest and the most prevalent method of vaccination is to use the whole disease-causing pathogen in a vaccine. This helps to produce an immune response similar to the natural infection. Modern vaccines use altered pathogens to reduce the risk of diseases.

 

The whole virus vaccines are of two types-

 

1. Inactivated: The disease-carrying virus or bacterium is taken and is rendered inactivate using heat, chemicals or radiation treatment. 

 

2. Live-Attenuated: A copy of a living but weakened version of the virus or something similar is used. The MMR vaccine (measles, mumps and rubella) and the chickenpox vaccine are examples of this type of vaccine. 

 

 

(B) Subunit Viral Vaccines

A subunit vaccine is different from the whole virus vaccine. Just as the name suggests, it only uses specific parts (subunits) of a virus or bacterium that needs to be recognized by the immune system. 

 

 This type of vaccine doesn’t contain the whole microbe or virus as a vector. Various kinds of subunits may be used like proteins or sugars. A lot of the common vaccines are developed in this format since these are not only effective but also safe. Subunit viral vaccines have been in use to protect from diseases such as tetanus and diphtheria. Subunit viral vaccines may be understood by studying the subunits of a virus that can be used-

 

1. Protein Subunit: They contain isolated and purified viral proteins and do not contain any live component of the pathogen. The antigenic parts of the pathogen create an immune response in a protected manner.

 

2. Virus-like Particles (VLP): VLP contains viral proteins that mimic the structure of the virus, but are not infectious since there’s no genetic material. Once the body has had an immune response to them, it will recognize the virus and prevent infection by providing immunity to that particular virus.

 

3. DNA-based and RNA-based: They contain a part of the virus’ own genetic code, just enough to trigger an immune response. The protein can then be produced directly at the cell. 

 

4. Non-Replicated Viral Vector: This type of viral vector contains viral genetic material packaged inside another harmless virus. This viral vector is enough to induce host response but will not replicate inside the host cells.

 

5. Replicating Viral Vector: This type of viral vector contains viral genetic material packaged inside another harmless virus which is used to deliver genetic code for antigen. This viral vector can copy itself, making it a convenient means to deliver vaccine antigens to select target cells or tissues. They trigger an immune response effectively yet safely.

 

For COVID-19, there are various vaccines that have been approved by various nations.
The following vaccines have been authorized and approved for use by the United States of America-

• Pfizer-BioNTech
• Moderna
• Johnson & Johnson

In India, different vaccines were created and approved. The vaccines were then mass produced and the vaccination drives were conducted to improve the rate of vaccination. The vaccines prevalent and approved in India are-

• Covishield
• Covaxin

Side effects of the vaccines-

Just like any other vaccine, mild to moderate side effects may be seen after having administered a COVID-19 vaccine. These side effects include fatigue, pain, chills, fever, headache, muscle pain, and diarrhoea and they mostly fade away in a few days. While it is not common, long-term side effects are possible.

Since none of the approved vaccines contain the live virus that causes COVID-19, a vaccine dose can’t make a person directly sick with COVID-19.

When a person experiences side effects, it usually means that the vaccine is working and the immune system is responding to the stimulus.

Side effects shouldn’t be a deterrent in the vaccination process as only mass vaccination will save the world from the virus that has caused a global pandemic.