Vaccines are biological preparations that provide immunity against infectious diseases by training the immune system to fight pathogens. India has emerged as a global vaccine hub, supplying over 60% of global vaccine demand through indigenous vaccine development.
Basic Principle Behind Vaccine Development
Mimicking natural infection: Vaccines imitate infections to safely activate the body’s immune defenses.
Antigen as the key component: Vaccines contain antigens that trigger antibody production. These may include:
Weakened or killed pathogens
Pathogen fragments or genetic material
Inactivated bacterial toxins (toxoids)
Types of vaccine platform:
Live-attenuated vaccines: Use weakened living pathogens, providing strong immunity but posing risks to immunocompromised individuals. Eg- MMR and Chickenpox vaccines.
Non-live vaccines: Use killed pathogens or subunits, making them safer but requiring booster doses due to shorter immunity. Eg- DTaP vaccine.
Addressing viral mutations: Vaccines for rapidly mutating viruses are periodically updated to maintain protection. Eg- Seasonal flu vaccines and COVID-19 boosters.
How Vaccines Work?
Immune system activation: Vaccine antigens are recognized as foreign threats, activating white blood cells to multiply and respond.
Antibody production: White blood cells produce antibodies that specifically identify and neutralize the pathogen.
Immunological memory: After the antigen is removed, memory cells remain in the body, providing long-term immunity.
Protection against disease: On future exposure, memory cells rapidly produce antibodies, preventing severe illness or death.
Approaches Adopted by Indian Vaccine Manufacturers for COVID-19
Inactivated whole-virion platform (Covaxin): Bharat Biotech and Indian Council of Medical Research developed a vaccine using chemically inactivated SARS-CoV-2 virus to safely trigger immunity.
Viral vector platform (Covishield): Serum Institute of India(SII) used a harmless chimpanzee adenovirus carrying spike protein genetic code to stimulate immune response.
Recombinant protein subunit platform (Covovax & Corbevax): SII and Biological E developed vaccines using purified spike proteins with adjuvants to induce antibodies.
DNA plasmid platform (ZyCoV-D): Zydus Cadila developed the world’s first human DNA vaccine using plasmid DNA delivered through a needle-free injector.
mRNA platform (GEMCOVAC-19): Gennova Biopharmaceuticals developed an mRNA vaccine using lipid nanoparticles to deliver spike-protein instructions safely into cells.
India’s diverse COVID-19 vaccine response-from inactivated vaccines to DNA and mRNA platforms-has strengthened its role as the Pharmacy of the World. Expanding indigenous R&D and ensuring timely immunization remain vital for achieving United Nations SDG 3(Good Health and Well-being)