2nd sero survey begins in Delhi, extended till Aug 7 due to lack of samples

A fresh sero-prevalence survey began on Saturday for a comprehensive assessment of the Covid-19 situation in Delhi, but not many samples could be collected due to the Eid holiday, officials said.

Hence it has been decided to extend the survey till Friday, an official said.

Originally a five-day exercise from August 1-5 that began with four districts on Saturday, it will span all districts and cover various demographic segments.

However, another source said one more district was covered on Saturday and rest six districts would be taken up on Sunday. Delhi has a total of 11 districts.

Not many samples could be collected on the first day since it was a festival. So, the survey will be carried for extra two days till August 7, according to an official.

The exercise is being undertaken for a comprehensive assessment of the Covid-19 situation in Delhi.

According to the survey's standard operating procedures handed out to the field units, each sample collection team is to collect 25-40 samples per day.

"All districts are to ensure that out of total number of samples, 25 per cent are of those younger than 18 years of age, another 50 per cent are in the age group of 18-49 years and remaining 25 per cent of those in the age group of 50 years or more," reads the SOPs issued by the Delhi's Directorate General of Health Services.

Also, selection bias must be avoided. The individual or household that was included in the previous round of sero-survey must be excluded, it added.

Teams in the field will collect the samples and will transport it the same day to the designated laboratories for processing. Sample collection must be completed latest by 2 pm so that samples reach the designated labs latest by 4 pm, reads the SOP.

As per the latest bulletin released on Saturday evening, Delhi recorded 1,118 fresh coronavirus cases, taking the tally to over 1.36 lakh, while the death toll from the disease mounted to 3,989.

The number of active cases was 10,596, down from 10,705 the previous day.

Health Minister Satyendar Jain told reporters on Saturday that the previous survey had indicated that about 24 per cent of sampled people in Delhi had shown presence of antibodies, meaning they had got infected and recovered.

The fresh survey is bring undertaken to find out the situation in the city since the previous sampling so better decisions can be made to tackle Covid-19, he said.

Earlier in the day, an official said 15,000 samples would be collected as part of this exercise, spanning different areas and age groups.

Representative samples will be taken from all the eleven districts.

A sero-prevalence survey involves testing the blood serum of individuals to check for the prevalence of antibodies against infection.

Jain had on July 22 announced that after analysing the results of the last survey, it was decided that more such exercises would be undertaken every month to formulate better policies for tackling the Covid-19 situation in Delhi.

The last sero-prevalence survey was conducted by the Delhi government in association with the National Centre for Disease Control (NCDC) from June 27 to July 10.

The second round would follow the same protocol as that was for the last survey, officials said.

The Delhi health department has prepared a detailed plan under which every district medical officer has been asked to conduct the survey in their respective jurisdictions, officials said.

All CDMOs have been be tasked with carrying out the survey in their districts. Random people will be tested for antibodies.

The last sero-prevalance survey had found that around 23 per cent of the people surveyed had been exposed to the novel coronavirus, the Centre had said.

The previous study had tested 21,387 samples. Prior to that, a similar exercise was carried out in April in containment zones only.

The Delhi government had decided to conduct more monthly sero surveys to find a greater percentage of such people who had got infected and recovered so as to formulate better policies for tackling Covid-19, Jain earlier said.