COVID-19 sero survey shows Delhi closer to herd immunity

Some respite from the coronavirus outbreak might be in store for Delhiites as the results of the fifth round of the sero-prevalence survey in the national capital has shown that its population is moving towards achieving herd immunity against COVID-19. The survey has shown that in a single district of the National Capital, 50-60 per cent of the sampled population has developed COVID-19 antibodies, according to a PTI source.

The survey, which was concluded a few days ago, had taken samples from over 25,000 people in various districts across Delhi, the survey officials told. Delhi's total population spread across its 11 districts is 2 crore.

"In one district, the sero-prevalence rate is between 50-60 per cent, indicating a large number of people have developed antibodies, so we can say the city is moving towards attaining herd immunity," a source told PTI without revealing the name of the district.

According to experts, herd immunity is developed if around 50-60 per cent of those tested for the survey have antibodies present in their bodies.

Herd immunity means that in any set of people in a community, after becoming affected by a disease, a large percentage have become immune to it as antibodies were developed in response to the pathogen. Hence, such people become a protective layer between those infected with the virus and those who have still not contracted it. Achieving herd immunity effectively breaks the chain of viral transmission.

This was the fifth sero-prevalence survey which was conducted in the national capital. The Delhi government has not officially released the findings from this survey yet.

The first round was conducted from June 27 to July 10 by the Delhi government in association with the National Centre for Disease Control (NCDC). It used 21,387 samples and found that around 23 per cent of the people surveyed had been exposed to COVID-19.

The survey round held in August last year showed that 29.1 per cent of people had antibodies. In the survey round held in months of September and October, the figures stood at 25.1 per cent and 25.5 per cent respectively.

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