During a press briefing on Friday, Dr VK Paul, Member of Niti Ayog (Health), said that the Indian Council of Medical Research (ICMR) is planning to conduct the country’s fourth national serosurvey this month.
The existence of Covid-19 antibodies in the human body can be detected via a serosurvey; the presence of antibodies indicates that the person has been exposed to the virus. Sero-surveys look at the liquid part of the blood, called serum, rather than the fluid in the nose, throat, and mouth. Sero-surveys provide us a broad view of how the infection is spreading.
This will be the ICMR’s fourth serosurvey in the country, following the third nationwide serosurvey that took place between December 17, 2020, and January 8, 2021. It will be held in 70 districts around the country, with children aged six and up participating. Paul emphasised the importance of state-wide serosurveys to “defend our geographies" from pandemic threats. At the district and state levels, he advised states to perform serosurveys at Covid-19 hotspots and infection hotspots.
The fourth survey will be the first to be carried out after vaccination has been made available to the general public.
“It helps us find out the infection rate and how many have anti-bodies, or how far are we from herd immunity. It will also tell us which party of the country has less positivity, Centre for Cellular and Molecular Biology (CCBM) advisor Dr Rakesh Mishra told ANI today.
“It will also tell us about anti-bodies in people who are already vaccinated. A large scale serosurvey in the country will be very useful," he said.
He said it looked like 80-90% of cases in most countries were due to the Delta variant. “But it will change in say two months with newer versions of the variant. Some reports in the UK suggested that Delta is acquiring some nutritions but that doesn’t mean it will be more harmful," he said.
What have serosurveys revealed so far?
According to the most recent survey, by January 8, at least one in every five Indians over the age of 18 had been exposed to coronavirus. The findings, according to experts, indicate that a huge chunk of the country — about 80% – is still vulnerable to the virus. Seroprevalence was also found to be 25.3 percent in children aged 10 to 17, and 25.7 percent in healthcare workers, according to the most recent serosurvey.
A serosurvey also provides nuanced information based on gender and occupation. In the most recent survey, women were found to have higher Covid-antibodies (22.7%) than men (20.3 percent ). It was also discovered that doctors and nurses were the most affected with a seroprevalence of 26.6 percent, followed by paramedical staff (25.4 percent), field staff (25.3 percent), and administrative staff (25.3 percent) among the 7,171 health care workers from taluk hospitals, community health centres, primary health centres, and other locations from each district covered in the serosurvey (24.9 percent ).
Si far, all three serosurveys have been done in 700 villages across 70 districts in 21 states across the country. Adults were polled from the second part of May to early June in the first study, and seropositivity was recorded at 0.73 percent. The second study, which took place in August and September, indicated that 6.6 percent of people aged 10 and up were seropositive.
Serosurveys, on the other hand, do not reveal if the group sampled is immune to future illnesses. It identifies all antibodies in the body, albeit not all antibodies are protective. Vaccination, in conjunction with Covid-appropriate behaviour, remains the most effective way to combat Covid-19.