Q. 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: 

Vaccine Development: Principles, Mechanisms, and Indian COVID-19 Vaccine Approaches

Vaccines are biological preparations that stimulate the immune system to recognize and combat specific pathogens, providing protection against infectious diseases. The basic principle behind vaccine development is to induce immunity without causing the disease itself.

The fundamental mechanism of how vaccines work involves:

• Introducing antigens: Vaccines contain weakened or inactivated pathogens, or specific components of pathogens (e.g., spike protein).

• Triggering immune response: The introduced antigens stimulate the immune system to produce antibodies and activate T-cells.

• Creating immune memory: This process generates memory B and T cells, allowing for rapid response to future infections.

• Providing long-term protection: The immune memory enables the body to quickly recognize and neutralize the pathogen upon subsequent exposure.

Indian vaccine manufacturers adopted various approaches to produce COVID-19 vaccines:

1. Inactivated virus approach:
– Bharat Biotech developed Covaxin using this traditional method.
– Whole SARS-CoV-2 viruses are chemically inactivated, preserving their structure for immune recognition.

2. Viral vector approach:
– Serum Institute of India produced Covishield under license from AstraZeneca.
– Uses a modified chimpanzee adenovirus to deliver the SARS-CoV-2 spike protein gene.

3. DNA vaccine approach:
– Zydus Cadila created ZyCoV-D, India’s first plasmid DNA vaccine.
– Delivers DNA encoding the spike protein, prompting cells to produce the antigen.

4. Protein subunit approach:
– Biological E developed Corbevax in collaboration with Baylor College of Medicine.
– Uses a specific part of the virus (receptor binding domain of spike protein) to trigger immunity.

These diverse approaches demonstrate India’s capability to leverage various vaccine technologies. Collaborations with international institutions and technology transfers played a crucial role in rapid vaccine development and production.

Conclusion: India’s multifaceted approach to COVID-19 vaccine development showcases its scientific prowess and contribution to global immunization efforts.