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Is a third vaccine booster dose needed? 7 experts weigh in

Experts remain divided on the efficacy of a third or booster dose of Covishield after the surprise proposal came from the chairman of SII Cyrus Poonawalla

August 19, 2021 / 09:35 IST
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Source: AP

Serum Institute of India (SII) Chairman Cyrus Poonawalla’s statement that a third or booster dose of Covishield is needed six months after the second dose of the vaccine, has elicited varying responses from the community of epidemiologists, biologists, virologists, and noted COVID-19 experts.

Many of them believe a third dose is not needed, some with significant caveats.

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The head of one of the largest vaccine companies in the world, Poonawalla said last week that he and several SII employees had taken the third dose of Covishield, AstraZeneca's vaccine against COVID-19, a PTI report said.

"After six months, the antibodies go down and that is why I have taken the third dose. We have given the third dose to our 7,000-8,000 SII employees. For those who have completed the second dose, it is my request to take a booster dose (third dose) after six months," the news agency reported, quoting Poonawalla.

COVID-19 Vaccine
Frequently Asked Questions

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How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
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