The Delhi government is expected to begin the seventh serological survey later this week, wherein part of data collection will be done through a mobile application, officials said.
A serological survey is done to find out how much percentage of the population have antibodies against COVID-19, either through natural infection or vaccination.
The government aims to collect 28,000 blood samples of random people from all 272 wards of the city. The result of the seventh survey will tell us the impact of the second wave of the pandemic, as the last survey was started in April, before the second wave and had to be cut short due to the spike in cases.
The result is also expected to be more specific due to a change in the procedure, officials said. “Till now, we have measured only IgG in the blood samples. But this time, we are planning to measure neutralising antibodies, which give better protection against the virus,” a Delhi government official told The Hindu.
Preparations have been done and the survey is expected to start in two to three days, an official said. “Whenever blood is collected from a person for the survey, they are also requested to answer a questionnaire. This time, we do it using an android-based mobile application, which will speed up our entire process. In the earlier surveys, the details were entered on paper at the ground level and then collated,” the official said.
Longest interval
Since the Delhi government started doing serological surveys for COVID-19 in June 2020, this is the longest interval between surveys. In June, the team that did the sixth serological survey had recommended the next survey in June end or July first week. The government did not follow this and did not officially release the results.
In August, Central government officials suggested at a Delhi Disaster Management Authority (DDMA) meeting for a sero survey among children to know their exposure. During the meeting, Dr. V.K. Paul, member NITI Aayog, also emphasised the “need for high quality sero survey”.
What is a serosurvey?
Blood samples collected from across the city are tested in a lab using antibody testing kits to understand whether the person was infected by the virus and developed antibodies. 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 developed immunity against it or it is due to vaccination. The first such survey, done in the city in June-July last year, had shown that 23.4% of the people surveyed had developed antibodies against the virus. Similar surveys in August 2020 showed that 29.1% people have antibodies, 25.1% in September 2020, 25.5% in October, and 56.13% in January.
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