Vaccine development relies on the principle of training the immune system to recognize and combat pathogens without causing disease. By triggering immune memory, vaccines provide long-term protection against infections. In response to COVID-19, Indian manufacturers adopted various methods, from viral vectors to mRNA technology.

Q.16 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 ?

Model Answer:

Introduction

Vaccines are biological preparations that provide immunity against specific infectious diseases. The basic principle behind vaccine development is to stimulate the body's immune system to recognize and combat pathogens, such as viruses or bacteria, without causing the disease itself.

Body

Basic Principle Behind Vaccine Development:

  1. Antigen Presentation:
    • Concept: Vaccines contain antigens, which are parts of the pathogen (such as proteins, sugars, or the whole pathogen in a weakened or inactivated form) that trigger an immune response.
    • Goal: The immune system recognizes these antigens as foreign and mounts a response against them.
  2. Immune Memory:
    • Concept: Once the immune system has been exposed to the antigens, it creates memory cells that remember the pathogen.
    • Goal: If the body is exposed to the actual pathogen in the future, these memory cells quickly recognize and neutralize it, preventing illness.

How Vaccines Work:

  1. Introduction of Antigen:
    • The vaccine introduces the antigen into the body, either through injection, oral administration, or nasal spray.
  2. Immune Response Activation:
    • The immune system detects the antigen and activates various immune cells, including T cells and B cells.
    • B cells produce antibodies specific to the antigen, while T cells help in the immune response and destroy infected cells.
  3. Formation of Memory Cells:
    • After the initial immune response, the body retains memory B cells and T cells that remember the antigen.
    • These memory cells provide long-term immunity by quickly responding to future exposures to the pathogen.

Approaches Adopted by Indian Vaccine Manufacturers to Produce COVID-19 Vaccines:

Indian vaccine manufacturers employed various approaches to develop COVID-19 vaccines, leveraging different technologies and platforms. Here are some key approaches:

  1. Inactivated Virus Vaccine:
    • Example: Covaxin by Bharat Biotech.
    • Method: The virus is inactivated (killed) using chemicals, heat, or radiation, so it cannot cause disease. The inactivated virus is then used as the antigen in the vaccine.
    • Advantages: Proven technology with a long history of use in vaccines for diseases like polio and hepatitis A.
  2. Viral Vector Vaccine:
    • Example: Covishield by Serum Institute of India (developed in collaboration with AstraZeneca and Oxford University).
    • Method: A harmless adenovirus (common cold virus) is modified to carry the genetic material encoding the spike protein of the SARS-CoV-2 virus. When administered, the body produces the spike protein, triggering an immune response.
    • Advantages: Strong immune response and the ability to induce both antibody and T-cell responses.
  3. Protein Subunit Vaccine:
    • Example: Corbevax by Biological E.
    • Method: The vaccine contains harmless pieces of the SARS-CoV-2 virus (such as the spike protein) rather than the whole virus. These protein subunits stimulate an immune response.
    • Advantages: Safe and stable, with a well-established manufacturing process.
  4. mRNA Vaccine:
    • Example: Gennova Biopharmaceuticals is developing an mRNA vaccine (HGCO19).
    • Method: The vaccine uses messenger RNA (mRNA) to instruct cells to produce the spike protein of the SARS-CoV-2 virus. The immune system then recognizes the spike protein and mounts a response.
    • Advantages: Rapid development and production, strong immune response.

Conclusion

The development of vaccines is based on the principle of stimulating the immune system to recognize and combat pathogens without causing the disease. Vaccines work by introducing antigens that trigger an immune response and create memory cells for long-term protection. Indian vaccine manufacturers adopted various approaches, including inactivated virus, viral vector, protein subunit, and mRNA technologies, to produce COVID-19 vaccines. These diverse strategies have contributed to the rapid and effective response to the COVID-19 pandemic, providing critical tools to control the spread of the virus and protect public health.

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