One in 15 people, or 6.6%, of people over the age of 10 in India, have been exposed to Sars-Cov2, the virus that causes coronavirus disease (Covid-19), as of August, according to The findings of Indian The Second National Sero Survey from the Council for Medical Research (ICMR) released Tuesday.
If extrapolated to the country’s population, this would mean that nearly 88 million people may have been silently exposed to the virus.
The second iteration of the ICMR national serosurvey covered 29,082 people and was conducted between August 17 and September 22 in the same 700 villages and districts in 70 districts in 21 states that were covered in the first survey. The first nationwide serological survey (conducted between May 11 and June 4) showed that the overall prevalence of infection was 0.73%.
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All the other parameters of the two surveys were similar, except for the target age group: in the first phase, the selected population was 18 years or older, and in the second phase, samples aged 10 years and over were included.
“We changed the age group in the second survey from 18 years to 10 years and over because the infection was also seen in the younger population. The Sero survey gives us the prevalence of exposure to the virus, but you may or may not have developed the disease, ”said Dr. Balram Bhargava, CEO of ICMR.
Approximately 3 ml-5 ml of blood sample were collected to study the presence of IgG antibodies against the Sars-Cov2 virus. IgG antibodies are the longest-lasting antibodies that help determine a past infection.
“How long in the past is a work in progress, but these develop about 2-3 weeks after you have contracted the infection and stay around for about 2-3 months,” Dr. Bhargava said.
Also read: One in 15 over 10 years exposed to Covid-19, reveals the results of the ICMR sero survey
Slum urban (15.6%) and non-slum (8.2%) areas had a higher prevalence of Sars-Cov2 infection than rural areas (4.4%), and the prevalence in adults ( older than 18 years) was also older (7.1%) the results show.
“It continues to show that a large percentage of the population is still susceptible to infection, so it becomes really important to follow appropriate Covid-19 behavior such as wearing a mask, maintaining social distancing, and observing hand hygiene.” said Dr. VK Paul, Member (Health), Niti Aayog.
Experts say that these types of serosurveys do not present the current picture. “This does not inform us about the current situation and that is the reason why it may not be really beneficial for making decisions at the policy level. However, for academic purposes, if someone wants to study the trajectory of the pandemic in India at some point later, it will help, ”said Dr Jugal Kishore, director of community medicine at Safdarjung Hospital.
Several state governments have conducted independent serosurveys that have shown a wide variation in results. Delhi had shown an infection prevalence of 23.5% and 29.1% during the first and second rounds of surveys. Initial findings from the third round of serosurveys in Delhi showed that approximately 33% of people have been exposed. These studies have also been conducted in Mumbai (57.8% in slums, 17.4% in slums), Ahmedabad (17.6%), Chennai (21.5%), Puducherry (4.9%, 22 , 7%) and Indore (7.8%). .
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