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Delhi close to attaining herd immunity as 50% population has COVID-19 antibodies: Sero survey

The latest sero-survey has found that every second person in Delhi has developed antibodies against the novel coronavirus. Meaning, out of the over two-crore people residing in Delhi, nearly one crore persons have already contracted COVID-19 and recovered from it.

January 25, 2021 / 20:15 IST
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Delhi conducted its fifth sero-prevalence survey in January and the results have revealed that the National Capital is inching closer towards attaining herd immunity against COVID-19.

The latest sero-survey has found that every second person in Delhi has developed antibodies against the novel coronavirus. Meaning, out of the over two-crore people residing in Delhi, nearly one crore people have already contracted COVID-19 and recovered from it. What is a sero-survey and will it help in the fight against COVID-19?

Though the Delhi government is yet to announce the result of the survey, a source privy to it has revealed: “In one district, the sero-prevalence rate is between 50-60 percent, indicating a large number of people have developed antibodies, so we can say the city is moving towards attaining herd immunity.”

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A population is deemed to have attained herd immunity if 50 to 60 percent of the people are found to have developed antibodies during a sero-prevalence survey.

Notably, this was the fifth sero-survey conducted in Delhi; it was kicked off on January 11 and 28,000 samples were collected during the exercise. 6.6% Indians aged above 10 were exposed to COVID-19 by August: Sero-survey

The first one was done in July 2020 and had revealed that 23 percent of the surveyed population had developed antibodies against COVID-19.

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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