What are key findings of 4th national COVID-19 serosurvey to test antibodies?

New Delhi: Two-third of Indians above the age of 6 had SARS-C0V-2 antibodies, show findings of the fourth nationwide serological survey conducted by the Indian Council of Medical Research (ICMR) in June-July. The survey results also suggest that about 40 crore people or one-third of the country’s population is still vulnerable to the novel coronavirus.

The survey was conducted across the country in June and July. Its findings are significant because this is for the first time children aged 6-17 years were included in the national serosurvey. The results of the survey were released by DG, ICMR, Dr Balram Bhargava.

What is the survey?

The ICMR has conducted the fourth round of national blood serum survey which tests for antibodies, known as a serosurvey, for Covid-19. The aim of the survey was to estimate the sero-prevalence of SARS-C0V-2 antibodies.

The survey was conducted in June and July, 2021 across 70 districts of 21 states. These are the same districts where three earlier rounds have been conducted during May-June (2020); August-September (2020); and December-January (2020-2021).

Who all did the survey cover?

The survey was conducted among 28,975 people. For the first time children aged 6-17 years were included in the survey. Besides, it included 7,252 healthcare workers.

What are the main findings of the fourth round of national serosurvey?

The results of the IMCR’s fourth round of national serosurvey shows that the overall sero-prevalence in the country was 67.6% in June and July, which is higher than the sero-prevalence rate recorded during the three earlier surveys – 0.7 percent during May-June (2020); 7.1 percent during August-September (2020); and 24.1 percent during December-January (2020-2021).

So, the latest findings of the survey suggest that two-third of the general population above 6 years have SARS-CoV-2 antibodies, which means that two-third of Indians have been exposed to novel coronavirus. It also shows that one-third of the population does not have antibodies, which suggests that about 40 crore people are still vulnerable to the novel coronavirus.

“In conclusion, two-thirds of the general population that is above the age of six years had SARS-CoV-2 infection. More importantly, a third of the population did not have any antibodies… 40 crore population of this country is still vulnerable,” Bhargava said, addressing a press conference.

“States/districts/areas without antibodies run the risk of infection waves,” Bhargava said.

The survey also shows that sero-prevalence was similar in rural and urban areas. It also suggests that 85 per cent healthcare workers had antibodies against SARS-CoV-2.

What does the survey say about children?

The survey findings shows that more than half of the children (6 -17 years) were seropositive. It means they have been exposed to Covid-19 in the past months. The sero-prevalence among children was 57.2 per cent in the age group 6-9 years and 61.6 per cent in the age group 10-17 years.

What are the implications of the latest findings of the serosurvey?

Bhargava says there is a “ray of hope” but there is “no room for complacency.” He emphasised on the need of maintaining Covid-appropriate behaviour and curbs on community engagement. He said societal, public, religious and political congregations should be avoided.