Bridging study of Covovax vaccine
GS Paper - 3 Biotechnology
Serum Institute of India (SII) CEO Adar Poonawalla said that the company planned to start its bridging study of the Covovax vaccine “soon”. It will also be stockpiling doses of the vaccine starting April. Covavax is SII’s version of NVX-CoV2373, the protein-based Covid-19 vaccine developed by Novavax, headquartered in the USA.
- In August 2020, the two companies announced an agreement under which Novavax had given SII the licence to manufacture and supply the vaccine in low- and middle-income countries as well as India.
- The agreement is expected to support the supply of a minimum of 1 billion doses of this vaccine in these regions.
- Like several other Covid-19 vaccines, Covovax targets the spike protein on the surface of the SARS-CoV-2 coronavirus — the protein that allows the virus to penetrate the human cell.
- Novavax has achieved this by engineering copies of the spike protein in the lab using the cells of a moth.
- Modified spike genes are placed in a baculovirus, which is known to infect insects. This virus is then used to infect the moth cells, carrying the spike gene into the cell.
- The cells then create the spike proteins, which are harvested. After they are purified, a certain dosage of these spike proteins is used as the vaccine.
- Once a person is given a shot of this vaccine, their body is expected to recognise these copies of the spike proteins as a foreign substance and build immunity against them. When the real virus tries to infect the cell, the body is expected to be able to fight it off.
- The vaccine recently showed an efficacy of 96.4% against mild to severe disease caused by the original strain of SARS-CoV-2 from ongoing late-stage global trials.
- Compared with this, Covishield (SII’s other Covid-19 vaccine) has an efficacy around 53% when the second dose is given less than six weeks after the first dose, which is the regimen followed in India.
- The efficacy of the AstraZeneca-Oxford vaccine, which Covishield is based on, varies based on the duration between the first and second shots and can go to nearly 79% if the gap is 12 weeks or longer.