COVISHIELD vs COVAXIN

Subject : Science & tech

Concept :

COVISHIELD

It is the name given to an Oxford-AstraZeneca Covid-19 vaccine candidate which is technically referred to as AZD1222 or ChAdOx 1 nCoV19.
It is a version of the vaccine developed by the University of Oxford in collaboration with Swedish-British drugmaker AstraZeneca.
Serum Institute of India (SII) is the manufacturing partner in India.

Constituents and Action:

It is based on a weakened version of a common cold virus or the adenovirus that is found in chimpanzees.
This viral vector contains the genetic material of the SARS-CoV-2 spike protein (protrusions) present on the outer surface of the virus that help it bind with the human cell.
The body’s immune system is supposed to recognise this protein as a threat, and work on building antibodies against it.

Significance:

It had triggered an immune response in humans against the novel coronavirus in early trials and is considered to be one of the global frontrunners for the Covid-19 vaccine.

COVAXIN:

It is India’s only indigenous Covid-19 vaccine.
Developed by Bharat Biotech, Hyderabad in collaboration with the Indian Council of Medical Research’s National Institute of Virology, Pune

Constituents and Action:

It is an inactivated vaccine which is developed by inactivating (killing) the live microorganisms that cause the disease.
This destroys the ability of the pathogen to replicate, but keeps it intact so that the immune system can still recognise it and produce an immune response.
It is expected to target more than just the spike protein.
It also aims to develop an immune response to the nucleocapsid protein (the shell of the virus that encloses its genetic material).

Significance:

COVAXIN is more likely to work against newer variants of the virus, including the UK variant, as it contains immunogens (epitopes) from other genes in addition to those from Spike protein.
Immunogen is a stimulus that produces a humoral or cell-mediated immune response, whereas antigens are any substance that binds specifically to an antibody.
All immunogens are antigens, but all antigens may not be immunogens.
Approval of COVAXIN ensures India has an additional vaccine shield especially against potential mutant strains in a dynamic pandemic situation.