Vaccine

Subject: Science and tech

Context:

There have been several announcements of companies either entering into agreements to make Covid-19 vaccines or announcing human clinical trials for their candidates in India in the last few months.

Concept:

Covishield  by University of Oxford-AstraZeneca

• This vaccine works on a mechanism that uses a weakened and non-replicating version of a common cold virus that infects chimpanzees to carry a code that will tell cells to build just the spiky outer layer of the SARS-CoV-2 virus (the spike protein).
• The body’s immune system is expected to recognise this as a threat and develop antibodies to fight the spike protein so that it will be ready in case the real virus tries to infect it.

ZyCov-D by ZydusCadila

• It uses a genetically engineered DNA molecule coded with the DNA sequence of the SARS-CoV-2 virus, against which the immune response is expected to be developed.

Covaxin by Bharat Biotech

• It aims to use dead virus, which is not expected to have the potential to infect or replicate in those injected with it, to induce an immune response by the body.

RBD protein vaccine by Baylor College of Medicine-Biological E:

• This is a recombinant protein vaccine candidate developed using the same traditional technique used to make vaccines against Hepatitis B.

HGC019 by Gennova Biopharmaceuticals-HDT Bio

• This candidate belongs to a newer category called ‘mRNA’ vaccines, which make use of the messenger RNA molecules that tell cells what proteins to build.
• The mRNA, in this case, is coded to tell the cells to recreate the Covid-19 spike protein–the spikes found on the surface of the SARS-Cov-2 virus. Once injected into the body, the cells will use the mRNA’s instructions, creating copies of the spike protein, which is in return expected to prompt the immune cells to create antibodies to fight it.