Initial results of survey show ‘high’ seroprevalence in Delhi: officials

‘It is a good sign as it means more people have developed antibodies against virus’

Published - July 08, 2020 11:22 pm IST - New Delhi

A doctor talking to patients at Guru Gobind Singh Hospital  on Wednesday .

A doctor talking to patients at Guru Gobind Singh Hospital on Wednesday .

After blood samples of over 22,000 people were randomly collected from the city to test for antibodies formed against COVID-19, the initial results of the serological survey showed at least 15% of them have developed antibodies against the virus, according to officials.

The data from the survey is still being analysed and a report is yet to be released by the government.

“Currently, the positivity rate [of COVID-19] in Delhi is about 9%-10%, but the initial results from the sero-survey is higher and is showing a seroprevalence of about 15%. Also, in one district [of the total 11], which was showing less positivity using other tests, the sero-survey is showing an initial trend of more than 25%,” an official source told The Hindu .

Most of the 22,000 samples have been processed.

Low risk

The source said that a higher seroprevalence is a good sign as it means a larger part of the population has developed antibodies against the virus and chances of them again contracting the virus are very low. Thus, they can break the chain of transmission of the virus and reduce the spread of the disease.

The positive results or seroprevalence of some districts are higher and the National Centre for Disease Control (NCDC) and the Delhi government is analysing the data, another official confirmed. “At least in four districts, the seroprevalence is more than 15%,” the official added.

The serological survey was started on June 27 and 22,823 random blood samples were collected from people of different age groups and demographics.

The blood samples were then tested in about 15 labs using antibody testing kits to understand whether the person was infected by the virus and developed antibodies against it.

Virus resistant

A positive result would mean that the person has developed antibodies against the virus. So, a seroprevalence of 15% means that 15 out of 100 people tested have developed antibodies against the deadly virus.

The serological survey is part of a ‘Revised COVID Response Plan’ by the Delhi government based on the directions from the Union Ministry of Home Affairs.

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