6th sero survey kicks off in Delhi amid Covid-19 case surge

The last such survey, samples for which were collected between January 11 and 21, found that over 56% of Delhi residents were exposed to the virus.

As the fourth wave of Covid-19 rages in the Capital, authorities in Delhi on Monday started collecting samples for the city’s sixth serological survey to determine the population-level prevalence of antibodies against the Sar-CoV-2 virus. Officials said sample collection will end in around 10 days.

A healthcare worker takes a swab sample from a man for RT-PCR test, at a testing centre in New Delhi. (AFP Photo)

The last such survey, samples for which were collected between January 11 and 21, found that over 56% of Delhi residents were exposed to the virus.

District and health department officials said field workers and auxiliary nurse midwifes, who were already working overtime, have now started collecting samples for the sero survey.

“It will take around 10 days to complete the drive, especially now that the Covid-19 cases are going up and workers are busy with contact tracing and containment work. Usually, we request nurses, doctors, and teachers from civic body and government hospitals to conduct the survey,” said a senior district official.

The prevalence of antibodies more than doubled from 25.5% during the October round of survey, largely owing to the third wave of cases in November, when 8,593 cases were reported in a single day at the peak.

The ongoing fourth wave of the infection has eclipsed previous records, with 11,491 new cases reported on Monday.

For the sixth round of the sero survey, 28,000 samples will be collected from the 272 municipal wards in Delhi, officials said.

“The study is designed to gauge the prevalence of antibodies; I cannot comment on the quality of the antibodies. We are expecting to see an increase in the level of antibodies in the current survey. However, it will not capture the current increase in cases as it takes some time to develop the antibodies,” said Dr Pragya Sharma, professor of community medicine, Maulana Azad Medical College, who is a part of the study.