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?
1. Basic principle: vaccines train the immune
Basic principle: vaccines train the immune system to recognise a pathogen’s antigens without causing the disease itself.
2. Vaccines present inactivated or weakened pathogens
Vaccines present inactivated or weakened pathogens, protein subunits, or genetic instructions as antigens to the immune system.
3. This triggers antibody production and memory
This triggers antibody production and memory B and T cells, which respond rapidly on later exposure to the real pathogen.
4. Bharat Biotech’s Covaxin used an inactivated
Bharat Biotech’s Covaxin used an inactivated whole-virus Vero-cell platform with an adjuvant.
5. Serum Institute of India produced Covishield
Serum Institute of India produced Covishield, the Oxford-AstraZeneca chimpanzee adenovirus vector vaccine, under licence.
6. Zydus Cadila’s ZyCoV-D was a DNA
Zydus Cadila’s ZyCoV-D was a DNA plasmid vaccine, the world’s first DNA vaccine approved for human use.
7. SII also manufactured Covovax
SII also manufactured Covovax, a protein-subunit vaccine, while Indian firms pursued mRNA platforms for boosters.
8. Mass manufacturing scale-up
Mass manufacturing scale-up, cold-chain logistics and CoWIN digital registration enabled India’s vast vaccination drive.
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