NEW DELHI, Sept. 1 (Xinhua) -- Health authorities in the Indian capital said the third phase of mammoth exercise to determine the spread of COVID-19 had kickstarted on Tuesday.
The serosurvey, as a part of the new COVID-19 response plan, will enable authorities to prepare a broad strategy to combat the ongoing pandemic in the capital city and outskirts.
Delhi Health Minister Satyendar Jain said the third phase will cover all 272 municipal wards to analyze the COVID-19 situation in Delhi at a "micro-level."
"The sample size this time will be 17,000 and the exercise will be carried out for seven days," Jain told media.
The last seroprevalence survey was held between Aug. 1 and Aug. 7, which showed that 29.1 percent of the people surveyed had antibodies against the COVID-19 infection. Around 15,000 samples were collected in this phase.
"The fresh round of serosurvey began today. This time we will be doing it ward-wise, so all 272 municipal wards of Delhi will be covered, plus two assembly areas. Sampling will be done for a week. After that, results should come in seven to 10 days," Jain said.
Compared to previous surveys which were done district-wise, this time samples are being collected ward-wise to analyze the situation in the city at a "micro-level," officials said, and the results of the third serosurvey will be announced by Sept. 21.
As per the standard operating procedure (SOP) that has been shared with the officials in the capital's 11 districts, half of the samples will be collected from individuals aged between 18 and 49 years while 25 percent each from the age groups that represent minors and people aged 50 years and above.
This is much like the same as done in the previous two sample collection drives.
During the first phase of the survey jointly undertaken up by the Delhi government and the National Centre for Disease Control (NCDC) from June 27 until July 10, a total of 21,387 samples were collected, of which 22.86 percent people were found to have developed antibodies against the Sars-Cov-2 virus causing COVID-19 disease.
Serology (antibody) tests are largely used for surveillance among the community. The tests can be used on people who have already been tested positive for the virus or even those who are asymptomatic. The exercise can reveal insights on immunity against COVID-19.
As per the Indian Council of Medical Research, periodic serosurveys are useful to guide the policymakers to conduct surveys in high-risk areas or vulnerable population who have been infected in the past and now recovered.
The survey will involve the collection of blood samples from randomly selected individuals. Blood samples will be collected for detecting IgG antibodies and it would be conducted using an IgG ELISA kit.
Delhi has the sixth-highest number of infections in India with 174,748 COVID-19 cases including 4,444 fatalities till date.
Currently, India is in the grip of the COVID-19 pandemic and the caseload seems to be increasing day by day.
The number of COVID-19 cases in the country has reached 3,691,166 on Tuesday, with 65,288 deaths. India is the third worst-hit country due to the pandemic.