New Delhi: The second Serological survey being conducted in the Capital, in addition to excluding people who were part of the previous study, will ensure that 25 per cent of the fresh samples are collected from people above the age of 50, according to the standard operating procedure prescribed for it.
The survey has roped in the Maulana Azad Medical College and while it was originally planned to be completed within August 5, a senior official has said that it has been extended to August 7. The fresh exercise is being undertaken for a comprehensive assessment of the COVID-19 situation in Delhi, but due to Eid holiday not many samples could be collected on Saturday, officials said.
The SOP for this survey being conducted by the Delhi government mandates that each sample collection team collect at least 25-40 samples every day.
"All districts are to ensure that out of the 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 SOP prescribed by the Delhi's Directorate General of Health Services.
Systematic Random Sampling methodology will be used for the collection of samples with the mandatory exclusion of individuals or households selected during the last serosurvey conducted in June-July, the SOP says.
The survey began with samples collection from various districts, including North Delhi and Northwest Delhi, to start with on Saturday. Sources said six districts are to be covered on Sunday.
According to the survey's standard operating procedure, "selection bias must be avoided" and any individual or household that was included in the previous round of sero-survey "must be excluded".
Teams in the field have been directed to collect the samples and transport them 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.
A senior government official on Saturday 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 11 districts.
A sero-prevalence survey involves testing the blood serum of individuals to check for the prevalence of antibodies against infection.
After the first serosurvey conducted by the NCDC, Delhi's Health Minister Satyendar Jain had said that the results of these studies, by nature, provide an outdated picture of the virus' prevalence and that in order to make informed policy decisions, the government would be conducting one such survey at the beginning of every month.
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. It had collected over 21,000 samples from across the city and found that around 22 per cent had been exposed to the virus at some point in time.
As per a bulletin released on Sunday, Delhi recorded 961 fresh coronavirus cases, taking the tally in the city to over 1.37 lakh, while the death toll from the disease mounted to 4,004.