Friday, 2 December, 2022
HomeHealthThis CSIR sero survey could partly explain why India is in the...

This CSIR sero survey could partly explain why India is in the grip of Covid wave again

CSIR conducted 2 follow-up sero surveys on people found to be seropositive in a nationwide survey last year. The one conducted after 6 months revealed an interesting finding.

Text Size:

New Delhi: At least 20 per cent of people found to be seropositive in a survey last year lost their neutralising antibody levels in the subsequent six months, according to a nationwide survey by the Council of Scientific & Industrial Research (CSIR). This, the researchers say, could partly explain why India is seeing a fresh surge in Covid-19 cases. 

A team of researchers from CSIR institutes across India conducted a sero-prevalence  survey in August and September 2020. The results showed that 1 million (10 lakh) people may have been exposed to SARS-CoV-2 — the virus that causes Covid-19 — since the beginning of the pandemic. 

Covid serological surveys analyse the number of people who have developed antibodies to the virus. Such surveys offer a rough estimate on how much of the population has been exposed to the virus. 

According to Shantanu Sengupta, professor at CSIR’s Institute of Genomics and Integrative Biology in Delhi, apart from revealing the extent of infections, their survey also showed that seropositivity levels within a population are predictive of the pandemic’s future trends.

The CSIR serosurvey was conducted across its constituent laboratories and centres all over India. Of the 10,427 volunteers surveyed, as many as 1,058 (10.14 per cent) tested positive for SARS-CoV-2 anti-nucleocapsid (anti-NC) antibodies, the kind that act against the outer protein shell of the virus. 

Three-fourth of those who were seropositive recalled no symptoms, according to the researchers. 

The researchers then conducted repeat serology tests on those found to be seropositive — on 607 people after three months and 175 people after six months. Among the latter, 20 per cent were found to be vulnerable to coronavirus reinfection, the researchers said.

“We were looking at the stability of the antibodies. We found that although in most people antibodies are intact even after six months, in 20 per cent of the cases the neutralising antibodies went below the acceptable threshold,” Sengupta said.

“This means that people who were infected six months earlier are now fresh candidates for reinfections. This would in part explain why we are seeing the rise in new Covid-19 cases,” he said.

The research has been accepted for publication in the peer-reviewed journal, eLife, and is likely to be published later this month.

Also Read: WHO and China probed coronavirus origin. And neither of them liked the results

Predicting trends

Speaking to ThePrint, Sengupta said serosurveys can be used to predict infections in the near future.

“We looked at the TPR (test positivity ratio, the share of positive diagnoses in Covid tests) 15 and 30 days before and after our serosurvey. Wherever the seropositivity was over 10 per cent, there was an immediate decline in TPR over the next 15 days,” he added. 

The research, Sengupta said, also revealed that national-level serosurveys are important to understanding the true extent of Covid spread, and the percentage of population that remains vulnerable. 

To elucidate the findings, Sengupta pointed out that several state- and city-level serosurveys had indicated up to 50 per cent seropositivity in states like Maharashtra, which continues to lead India’s Covid surge. A survey conducted in Pune between July and August, for example, showed over 50 per cent seropositivity.

“However, when we conducted a serosurvey of Pune, we found a seropositivity of less than 10 per cent,” Sengupta said. 

“The previous survey conducted (by IISER), which had shown high seropositivity, focused on the top five worst-affected districts of Pune. Naturally, those areas are bound to have high (sero)positivity,” he said. 

The recent surge in Covid cases in the city indicates that the number of people initially exposed to the virus was in fact much fewer than estimated, he added. 

Local serosurvey results reported by the media made people complacent, Sengupta added, with many believing that the population in their region had achieved herd immunity to Covid-19.

(Edited by Sunanda Ranjan)

Also Read: Kerala sero survey finds 10.76% people with Covid antibodies, police personnel top the list


Subscribe to our channels on YouTube & Telegram

Support Our Journalism

India needs fair, non-hyphenated and questioning journalism, packed with on-ground reporting. ThePrint – with exceptional reporters, columnists and editors – is doing just that.

Sustaining this needs support from wonderful readers like you.

Whether you live in India or overseas, you can take a paid subscription by clicking here.

Support Our Journalism


  1. This is a fine article.
    Great reporting by Print science reporter.
    I got good insights into the second wave because of this article.

  2. 😊The Actual/Real Data-Figures of Corona infected and Corona Dead People in India is Ten times higher than the Fake and False Data-Figure Published by this Feku Government.😊

  3. This is sound science that provides a good explanation for what is going on.

    That is also why it is of no interest to most readers or columnists at this website. Small wonder no one else has bothered to comment on it or reference it in their articles.

    • Decision makers appear to be averse to drawing conclusions which are uncomfortable and call for preparation and action beforehand.

  4. It is amazing that in this country we want to manage things without measuring them first. If the covid-19 were to continue to spread at the current rate and speed very soon we will not know who has died. All these people will go theirs graves with their privacy and anonymity intact.
    There are already reports of ambulances waiting in “Q” to off load the dead at the crematoriums.
    That ONE AADHAR CARD which was opposed and was in the courts for years would have been a solution to so many problems, but then hiding the stolen money was more important, and who cares, who pays the price?
    Do not know how any survey can be relied upon if the data collection is based on” chalta hai.”

  5. Month of April in 2021 is stirring woeful momentum of COVID19 pandemic by each passing day in India as well.
    (A). There are many woeful pieces of news on COVID-19 front across the world, India as well during month of April 2021 being learnt through reports. While other States reeling under the COVID-19, mutated or new variant said to have come from UK or Brazil, are mulling imposing of stricter restrictions in the face of mounting worries, Maharashtra government announced new restrictions effective at 8PM on 14 April, 2021 for 15 days, in the whole State. This is only four hours prior to the date identified by this Vedic astrology writer for major worrisome milestone concerning COVID-19 pandemic or new variant in, among others, Maharashtra. Through the predictive alert in the article ,as follows , published at on 3 April, 2021, this writer had identified the period from 15 to 19 of April 2021 as one carrying major worrisome concerns in vulnerable States of India.
    “Major worrisome concerns in India during a period of nearly two months from about 7 April to 31 May 2021, calling for more care and appropriate strategy. Such strategy may have to be continued as long as 10 August 2021 in some form or the other”.
    Link to reach the article:-
    (B). A longer prior similar predictive alert for more care and appropriate strategy was sounded by this writer, through article ‘ India in the year 2021 – planetary impacts interpreted’ published at on 7 September 2020. The related text of the predictive alert in the said article reads as follows:-
    “( 5 ). The time – period of one and a half month spawning over second half of April to full May ( 15 April to 31 May ) in 2021 , looks to be one of strategy to vitalize farmers , agriculture and crop-shortages. Cost of energy resources like gas , oil , power , can either jump or some issues concerning production , storage , and distribution of these may get obstructed. Shortages of food , eatables and life-saving medicines can be in close focus. The right course can be to get involved on war footing as soon as any related issue comes to notice. Advice of best and credible experts in the related field may be had without loss of time , and acted upon to provide cover. Within this period of 15 April to 31 May , the one of 11 days from about 21 May to 31 May seems to be calling particular attention. The compulsive and restrictive nature of times may present situations before Delhi to either bear the enormity of worrisome concern or to take recourse to a bit contrary to certain principles or policies hitherto pursued. A decision to be taken may be hard but there may not be a broad choice available”.
    It may be noticed that predictive alert about shortage of life-saving medicines, compulsive and restrictive nature of times, taking recourse to extra-ordinary decisions and no broad choice than to take hard decisions, during about 15 April to 31 May 2021, are indicated there. These are reaching our ears and eyes these days in April 2021 through news TV Channels.
    Link to reach the article:
    (C). A still pretty prior predictive alert for more care and appropriate strategy in relation to COVID-19 and other major worrisome concerns was sounded by this writer through another article ,as follows, published at on 16 May 2020, closely a year ago.
    “ When is the world coming out from the dreadful grip of COVID-19? W.H.O. Chief said on 21 April 2020: The worst is not yet over”.
    The related text is reproduced here from the article:-
    “One more alert prediction here for exercising more care and appropriate strategy. A period of nearly one and a half month from mid-April to 31 May in 2021 , particularly last eleven days of May 2021 would call for more alertness and appropriate strategy. In the absence of alertness and appropriate strategy , COVID-19 can re-emerge with greater strength and mischief in vulnerable most parts of the world. The planetary impact appears to be prone to suggest another reading covering mid-April to 31 May in the coming year 2021 – full-fledged war somewhere , could even be something most dreaded WW3 besides crisis in economy , trade and food sectors”. This predictive alert was flashed to a number of news portals and newspapers in India as well at that stage of time near May 2020.
    Besides woeful fury of COVID-19 pandemic or newer forms of coronavirus said to have come from other countries, we are also hearing news reports of two to three fronts of war-like scenario – Taiwan , Ukraine and Middle-East.
    The aforesaid details are suggestive of meaningfulness of the predictive alerts, so prior.

Comments are closed.

Most Popular