The Delhi government has started a fifth serological survey to find the percentage of the population that has developed antibodies against COVID-19, an official source told The Hindu .
Blood samples of random people will be collected to check how many of them have developed antibodies against the virus.
“This is the largest such survey done by the government in terms of sample size and 28,000 samples will be collected. The aim is to get an idea about the situation before citizens get the vaccine,” a Delhi government official said.
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The Delhi government is yet to make the decision to conduct the survey public.
“The sample collection started on Monday and about 9,000 samples have been collected so far. The sample collection is expected to be completed by January 21 and results are likely to be out in the first week of February,” the official said.
The first such survey done in the city in June-July had shown that 23.4% people had developed antibodies. A survey in August showed 29.1% people had antibodies, 25.1% in September, and 25.5% in October.
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The blood samples will be tested using antibody testing kits. A positive result would imply that the person has developed antibodies against the virus. This means that the person was infected at some point by the virus and now has developed immunity against it.
When a larger part of the population develops antibodies and becomes immune to the virus, the chain of transmission of the virus is broken and this reduces the spread of the disease and this is called herd immunity.
So, a higher value of sero prevalence is favourable.
As per experts, the result of the serological survey has to be about 50-60% to attain herd immunity.
357 new infections
Delhi on Wednesday reported 357 new COVID-19 cases in the last 24 hours, taking the total to 6,31,249. The death toll has risen to 10,718 with 11 more fatalities reported in a single day. There are now 2,991 active cases.