COVID-19 Vaccination: Coronavirus Vaccines Explained

India will launch one of the world’s largest immunization programs today.

new Delhi:

India will on Saturday launch one of the world’s largest vaccination programs with vaccines manufactured in the country – one developed by the University of Oxford and AstraZeneca, the other with a state-run institute by India Biotech International. First the vaccine will be held by 3 crore health and other frontline workers, followed by 27 crore or above 50 old people with high risk. Here is a look at the technology behind the two drugs, which will be given out.


Developed by Oxford University and the British-Swedish pharmaceutical company AstraZeneca and built by the Pune-based Serum Institute of India, Covishield has emerged as the most promising vaccine for countries like India where cost and logistics are an important consideration.

Unlike Pfizer and Modern Vaccines, which use a new approach called mRNA, making them more complex, fragile, and requiring ultracold temperatures, Covishield is a vector vaccine that is slow but inexpensive and importantly, Can be kept at standard refrigerator temperature stable for up to six months.


The vaccine uses a weaker version of a common cold virus called adenovirus that affects chimpanzees but does not infect humans. It binds to cells and injects DNA that tells them to form coronavirus spike proteins – structures on the surface of the coronovirus, giving it a studded appearance.

It attracts the attention of the immune system that identifies it as an alien and builds defenses to attack the actual coronavirus when an infection occurs.

Initial results published by researchers at Oxford-AstraZeneca in the UK showed that the vaccine was about 70 percent effective.


Developed by the Indian biotech company Bharat Biotech and the Indian Council of Medical Research (ICMR), the country’s top clinical research institution, Kovaxin is the second vaccine to be approved by the government.

It is an inactivated vaccine – one of the oldest methods to vaccinate people – meaning it uses whole, inactive viruses that are injected to trigger an immune response. These entire batches of coronaviruses must be “killed” using a chemical or heat and are then made a long process.


Chinese companies Synovac and Sinpharma are also using the same technology for their coronavirus vaccines.

There are some concerns about covaxin because its efficacy has not yet been proven in Phase 3 clinical trials, unlike Povicield and Vaccine by Pfizer and Modern. While the first two stages of vaccine tests usually find out if they are safe, the third phase usually shows whether the vaccine is effective.


Phase 3 trials for covaxin are still ongoing and this has worried some health experts who believe it, as the vaccine has only “clinical-trial mode” approval.

This month experts from India’s drug regulator recommended strict monitoring for the vaccine, as is done during clinical trials, and the government ordered 55 lakhs or only half as many doses of covaxine as covixil . Brazil became the first foreign country to sign an agreement to buy Indian shots this week.


Among the vaccines yet to come to India are those made by the American pharmaceutical firm Pfizer and its German-based partner BioNotech and another American company Moderna which are being used in the US, UK and other countries.

Both messengers use ribonucleic acid or mRNA, a type of genetic software that tells cells to form a piece of coronovirus spike protein, protecting them from infection. The approach can quickly produce a vaccine because scientists need only the genetic sequence of the virus, making it a front for the pandemic vaccine years ago.

Russia’s Sputnik V vaccine, which has been cleared by eight countries so far, is involved in the final phase trials in India after completing Phase 2 studies. An adenoviral vector vaccine, like Covishield, is expected to soon apply for emergency use approval in the country.

American multinational Johnson & Johnson’s vaccine arm Janssen Pharmaceuticals has also said it hopes to bring its single-shot coronavirus vaccine back on track in March and expects how effective it will be by the end of this month or early February. Will happen. It is also a vector vaccine.

(With inputs from agencies).



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