182 people covered under Covid-19 sero-survey, 32 found to have developed antibodies

The district administration has till Thursday tested at least 182 people as part of its serological survey to check for the undetected community transmission of

The district administration has till Thursday tested at least 182 people as part of its serological survey to check for the undetected community transmission of Covid-19.

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The health department on Thursday collected samples of 90 people to check for coronavirus antibodies in their blood serum. The sample was collected from Tigra, one of the worst-affected areas in the district, which has reported more than 226 cases.

Till now, tests showed, at least 32 people had developed antibodies against coronavirus.

Earlier this week, the health officials had collected 92 samples from pockets like Dundahera, Sirhaul, Pataudi, sector 14, among others, for antibody testing.

A serological survey includes IgG Enzyme Linked Immunosorbent Assay (ELISA) test. It estimates the proportion of population exposed to SARS-CoV-2 infection. The IgG test is not useful for detecting acute infections but it indicates episodes of SARS-CoV-2 infections that has happened in the past. The test is approved by the Indian Council of Medical Research (ICMR) for its high sensitivity and specificity. The test has been conducted in 75 districts across the country as part of a study. It was found that less than one percent of the population – 0.73% - in non-containment zones was found to have contracted the virus.

The sero survey has to be done in 460 people across different pockets of the city. Along with Gurugram, four other districts – Faridabad, Ambala, Panchkula and Sonepat – are also being covered in the survey.

Dr Virender Yadav, chief medical officer of the district, said, “Blood samples of only those people have been taken who have had high exposure to the contagious infection. It includes people who came in contact with a large group of people on a daily basis, such as health workers, police personnel, taxi drivers and sanitation staff among others.”

For conducting the survey, five mililitre blood samples is collected from the subjects. It is then put in a machine where blood and plasma are separated. The plasma is then used to detect antibodies developed against Covid-19 in the body. The city has received five sets, having 92 kits each, for conducting the survey. Ambala and Panchkula have got two sets each, while Faridabad and Sonepat have got five sets each. Each kit can be tested together in a single run of two and a half hours.

Yadav said that the sero surveillance was started earlier this week and 50% of the kits are being used on patients who tested positive in the last two weeks. The remaining will be used on people who confirmed negative. “Out of 92 people tested, 32 had IgG antibodies,” said Yadav.

The team had collected 92 samples earlier this week, which included samples of 50 people, who had recovered from Covid-19 in the past. The remaining 42 samples were of those who had no history of Covid-19. Of these 92 samples, only 32 — 26 in the first set and six in the second — were found to have IgG antibody in their blood serum. Studies shows, the IgG antibodies start appearing two weeks after the onset of infection.

Gurugram is about to breach the 5,000 mark in Covid-19 cases, and going by the future projections it can reach 7,000 mark by the end of June. Yadav said that the results of sero-survey, the rapid antigen detection test and routine RT-PCR will help in identifying the appropriate health intervention required to control the surge in numbers.