NEW DELHI: Hyderabad-based
Bharat Biotech has asserted that its Covaxin can be more
effective against mutant strains of coronavirus amid doubts over the efficacy of the indigenously developed vaccine.
Opposition leaders as well as experts have questioned the government's "hasty" approval to the India-made vaccine without the publication of the Phase 3 trial data.
Dr Krishna Ella, the company's chairman and managing director, said that emergency use authorisation to Covaxin is justified since it can be more effective against newer strains like the one detected in the United Kingdom recently.
“It’s only a hypothesis right now... Just give me one week’s time to come out with the data. I am confident it will work,” he said on Monday.
The director-general of the
Indian Council of Medical Research (ICMR), Dr Balram Bhargava, too, had expressed confidence the vaccine would be effective against new variants of the coronavirus. ICMR and the National Institute of Virology (NIV) worked with Bharat Biotech to create the vaccine.
To be clear, Pfizer, Moderna and AstraZeneca, too, have said their vaccines would be effective against the new variant of the
virus first identified in the UK, since the mutations on it, including on the spike protein, have not drastically changed its characteristics.
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Coronavirus in India: Live updatesBut there is a particular reason for Bharat Biotech’s confidence in its product: The vaccine is not relying on the production of spike protein to prompt an immune response but packs the actual virus itself, albeit inactivated, to kickstart the immune response.
Covaxin is an inactivated virus vaccine — a tried and tested science that has been used to develop vaccines against polio, rabies and hepatitis A.
The NIV, alongside the ICMR, isolated samples of the coronavirus that was in circulation in the country.
These viruses are then inactivated using chemicals so that they can no longer replicate thus making them incapable of causing Covid-19. During an infection the virus replicates itself in our body after entering the cell, creating new copies.
The virus then is mixed with adjuvants to form the basic block of the vaccine, which when administered causes the immune system to wake up and begin its self-defence mechanism — summoning the B cells to create antibodies.
The vaccine also prompts memory B cells, which can come to assistance once the antibody levels taper off — an expected process.
Hence, Bharat Biotech believes that by not relying solely on the spike protein, it has a better chance against new variants of the virus.
Pfizer’s and Moderna’s vaccines, on the other hand, pack genetic material — messenger RNA — that instruct our cells to produce spike proteins, duping our immune system to believe the host has been infected.
The Oxford/AstraZeneca vaccine is based on a weakened version of a common cold virus (adenovirus) in chimpanzees which has been genetically changed to stop Covid-19 replicating in humans