[Model Answer QP2022 GS3] What is the basic principle behind vaccine development? How do vaccines work? What approaches were adopted by the Indian vaccine manufacturers to produce COVID-19 vaccines?

Basic Principle behind vaccine development 

Vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body. Newer vaccines contain the blueprint for producing antigens rather than the antigen itself. Regardless of whether the vaccine is made up of the antigen itself or the blueprint so that the body will produce the antigen, this weakened version will not cause the disease in the person receiving the vaccine, but it will prompt their immune system to respond much as it would have on its first reaction to the actual pathogen.

Some vaccines require multiple doses, given weeks or months apart. This is sometimes needed to allow for the production of long-lived antibodies and development of memory cells. In this way, the body is trained to fight the specific disease-causing organism, building up memory of the pathogen so as to rapidly fight it if and when exposed in the future.

How do vaccines work?

1. To understand how vaccines work, it helps to first look at how the body fights illness. When germs, such as bacteria or viruses, invade the body, they attack and multiply. This invasion, called an infection, is what causes disease. The immune system uses your white blood cells to fight infection. These white blood cells consist primarily of macrophages, B-lymphocytes and T-lymphocytes
2. The first time the body is infected with a certain germ, it can take several days for the immune system to make and use all the tools needed to fight the infection. After the infection, the immune system remembers what it learned about how to protect the body against that disease. If your body encounters the same germ again, the T-lymphocytes recognize the familiar germ and the B-lymphocytes can produce antibodies to fight off infection.
3. Vaccines can help protect against certain diseases by imitating an infection. This type of imitation infection helps teach the immune system how to fight off a future infection. Sometimes, after getting a vaccine, the imitation infection can cause minor symptoms, such as fever. Such minor symptoms are normal and should be expected as the body builds immunity.
4. Once the vaccinated body is left with a supply of T-lymphocytes and B-lymphocytes that will remember how to fight that disease.

Approaches were adopted by the Indian vaccine manufacturers to produce COVID-19 vaccines

COVAXIN	Developed by Bharat-Biotech. India’s first indigenous, whole-virion, inactivated vaccine for the treatment of the highly infectious disease Covid-19. The vaccine is injected directly into the deltoid muscle, which is accessible in the upper arm
COVISHIELD	Developed by the University of Oxford in collaboration with Swedish-British drugmaker AstraZeneca. Serum Institute of India (SII) is the manufacturing partner in India. It is based on a weakened version of a common cold virus or the adenovirus that is found in chimpanzees.

Conclusion

The COVID-19 vaccine introduction is the world’s largest vaccination drive. The introduction of COVID-19 vaccine is a major step towards reducing the spread of the pandemic and further reducing the associated disease and deaths.