Q.For mass vaccination in India, _____ COVID vaccine, produced successfully by using attenuated corona virus particles, was used.

Among India's COVID-19 vaccines, Covaxin (by Bharat Biotech, developed with ICMR) is the one made from whole SARS-CoV-2 virus particles that were rendered non-infectious, unlike Covishield (viral vector) or ZyCoV-D (DNA vaccine).

During India's mass COVID-19 vaccination drive, several vaccine platforms were used, each based on different microbiological/biotechnological principles:

• Covishield - an adenoviral-vector vaccine (Oxford-AstraZeneca formula, manufactured by Serum Institute of India), which uses a harmless chimpanzee adenovirus engineered to carry the gene for the SARS-CoV-2 spike protein - not a whole-virus-particle vaccine.
• ZyCoV-D - a plasmid DNA vaccine (Zydus Cadila) that delivers spike-protein-coding DNA directly, needle-free, not a whole-virus vaccine. …

The smallpox vaccine uses live vaccinia virus, not the smallpox-causing variola virus itself.

Vaccinia virus is antigenically similar to variola virus (the causative agent of smallpox) but causes only a mild, localized infection in humans. Introduced into the body, it stimulates the immune system to produce antibodies that also protect against the more dangerous variola virus — the basis of Edward Jenner's original vaccination principle. Variola is the sm …