COVID-19 in India: Fourth ICMR survey results show 67.6 per cent seropositivity

The results of the fourth nationwide ICMR survey show unprecedented levels of SARS-CoV-2 antibody seroprevalence while the rate of vaccination in India continues to be far below the level needed to vaccinate the entire adult population by the end of 2021.

Published : Jul 25, 2021 06:00 IST

Blood samples collected as part of the Statewide serosurveillance by the Directorate of Public Health in Chennai on November 11, 2020.

Blood samples collected as part of the Statewide serosurveillance by the Directorate of Public Health in Chennai on November 11, 2020.

As of July 21, according to Our World In Data, 13.36 per cent of the global population had been fully vaccinated, while 26.75 per cent had received at least one dose. The corresponding figures for India were lower, at 6.35 per cent and 23.93 per cent respectively. Advanced countries like the United Kingdom, the United States, France, Germany and Italy are of course far ahead in the vaccination race, with 42 per cent to 53 per cent of their populations having been fully vaccinated and 56 per cent to 70 per cent having received at least one dose. The number of test-confirmed cases per million population in these countries are also four to five times the Indian number. Yet, it is the Indian population which seems to have the highest proportion of people carrying COVID-19 antibodies. This, characterised by the health establishment as a “ray of hope”, is actually testimony to the failure of the government to check the spread of a rampant virus.

The preliminary results of the fourth nationwide seroprevalence survey conducted by the Indian Council of Medical Research (ICMR) in June-July were shared at a media briefing on July 20. According to the estimates emerging from this, 67.6 per cent of the Indian population across all age groups were found to be carrying SARS-COV-2 antibodies. This is up from the 24.1 per cent reported by the last survey conducted in December 2020-January 2021, while the first (May-June 2020) and the second (August-September 2020) surveys had reported figures of 0.7 per cent and 7.1 per cent respectively.

Also read: COVID-19 in India: False positivity amidst declining second wave?

Between the third and the fourth surveys, two things happened. One was the country’s COVID vaccination programme, launched on January 16, and the other, the second COVID wave which began in the second week of February. There can be little doubt that it is the latter rather than the former that is responsible for such a sharp rise in the seroprevalence percentage, since less than a quarter of the population had received at least one vaccine dose even as late as July 20.

High seroprevalence

Indeed, 62.2 per cent of the sample group of the fourth ICMR serosurvey comprised those who had not received any vaccination, and the seroprevalence even in that category was found to be as high as 62.3 per cent. Among those who had received vaccinations, the presence of antibodies was detected in 89 per cent among those who had received both doses and 81 per cent among those who had received one dose. In other words, around two-thirds of the population with COVID antibodies had acquired them from an infection or exposure to the virus and not from vaccination. Given that this population would be close to 90 crore, the actual number of Indians who had contracted COVID-19 at least once would be in the range of at least 55 to 60 crore (or 550 to 600 million). This is several times the 31 million-odd test-confirmed cases reported in India so far.

Yet, the increase in the proportion of the population with antibodies from 24.1 per cent to 67.5 per cent actually parallels the nearly three-fold increase in the cumulative number of test-confirmed cases in India between January 15 and July 15. In other words, the proportion of infected people not covered by testing has not changed dramatically. Further, the ICMR survey figures are also close to the interim results from the ongoing WHO-AIIMS multi-centric population-based seroepidemiological study which were announced in mid June.

The case of U.K.

A scrutiny of nationwide studies compiled by SeroTracker, a Public Health Agency of Canada-supported knowledge hub that tracks and records the findings of SARS-CoV-2 serosurveillance efforts worldwide , reveals that such high levels of COVID seroprevalence as shown by the fourth ICMR survey are not to be found elsewhere in the world. Even countries which have vaccinated a large part of their population have not shown such a high level of seroprevalence.

Also read: Children as victims of the pandemic

For instance, the sixth round of REACT-2 (Real-time Assessment of Community Transmission-2), a community survey of adults in the U.K., estimated that antibody prevalence in mid-May was 61 per cent, at a time when 69 per cent of adults had received at least one dose of vaccine, with 39 per cent having had both doses. In comparison, the seroprevalence at the end of January, by which time the U.K. had experienced two waves of the pandemic, was just 14 per cent. This substantial increase in the U.K.’s case was therefore a reflection of the impact of vaccination, which began there in December 2020. This is in marked contrast to the Indian story.

The “ray of hope” attributed to the results of the fourth ICMR survey hints at the possibility of the Indian population acquiring something like “herd immunity”, though this specific expression was not used. This was, of course, qualified with statements to the effect that 40 crore people (those not carrying antibodies) were still vulnerable to catching the infection and that regional variations existed at the level of seroprevalence.

However, there is some contradiction between seeing such a high seroprevalence in a positive light or as an achievement and being simultaneously “concerned” about further spread.

If at all, a high seroprevalence of COVID-19 antibodies can be described as the only silver lining of the abysmal failure of the Indian government’s pandemic containment strategy. But for that, the government would first have to admit its failure. There is little to be proud about the fact that India was not able to prevent so many millions from getting infected and that its testing capacity and numbers fell so short of the requirement. Unfortunately, honest admissionof the truth and squarely facing the facts have not been a hallmark of the Narendra Modi government’s COVID response strategy. Using the absence of data as a pretext to deny that any Indians died during the second wave owing to shortage of oxygen is another recent instance of the government’s proclivity to twist facts to suit the purposes of constructing a false narrative.

One of the fallouts of the fourth ICMR serosurvey results that the government may not have wanted is that these results reaffirm the massive under-counting of not only cases but also COVID deaths in India. If even half a per cent of the 550 million of those who were definitely infected died, the number of COVID deaths would be in the range of 2.75 million, over six times the official death count, which stood at under 4.2 lakh on July 22.

The CGD study

Interestingly, an independent set of estimates of “excess mortality” in India during the pandemic were released and gained publicity at the same time as the ICMR Survey results. These estimates were from a study, published by Center for Global Development (CGD), a U.S.-based think tank, and co-authored by India’s former Chief Economic Adviser, Arvind Subramanian, which called the COVID pandemic “India’s worst human tragedy since partition and independence”. This study made use of civil registration (CRS) data, serosurvey results combined with international age-specific COVID fatality rates, and the Centre for Monitoring the Indian Economy (CMIE) consumer pyramid household survey (CPHS) to generate three different estimates of excess mortality. These estimates ranged from 3.4 million to 4.9 million. The figure that was based on serosurvey results was the intermediate one of 4 million. While the fourth ICMR survey results were not available for this study, it made use of the numbers that came from the WHO-AIIMS estimates.

Also read: COVID-19: No endgame in sight

This study also indicated that the first wave may have been more lethal than previously thought, even though the concentration of a large number of deaths in a short period of time during the second wave may have rendered the undercounting of fatalities more visible. Meanwhile, even the official death count during the second wave increased significantly on some days as previously unrecorded deaths entered the counts of some States following reconciliation exercises. With these, the total official COVID dead count during the second wave (from February 9 onwards) touched 2.64 lakh, more than 70 per cent of which happened, or were recorded, after May 6 or the peak of the second wave.

Internationally, COVID-19 cases are on the rise again, with several countries experiencing new surges driven by the Delta variant of the virus. This includes highly vaccinated countries like the U.K. and the U.S., partly because vaccines are not 100 per cent effective in preventing infection and almost all have reduced efficacy against the new strain, but also because a significant unvaccinated or partially vaccinated population exists everywhere. In India, too, this number is exceptionally large and includes more than 84 per cent of all adults. Whether the exposure to the infection indicated by the seroprevalence will act as a protection for many of them and for how long is as yet unknown, even as uncertainty continues to dog India’s vaccination drive.

The number of vaccination doses administered in the weeks that ended on July 5, July 12 and July 19 were, in each instance, more than 10 million lower than the “record” level of 42 million attained in the week that ended on June 28. In other words, India’s vaccination speed still continues to be far below the level needed to vaccinate the entire adult population by the end of 2021. With 65 per cent of Indian adults yet to receive any vaccination and another 26 per cent having been administered only one dose, even the modest target of achieving full vaccination of three-quarters of the Indian adult population by the end of the year would need at least 45 million vaccines to be administered each week. Every week that the country falls short, and the more it falls short, the greater will be the number of vaccine doses needed in the remaining weeks of the year.

Also read: Under-reporting of pandemic toll

Meanwhile, the declining trend in test-confirmed cases has also clearly lost steam as the nationwide numbers are proving increasingly resistant to being pushed down further. There are, of course, significant regional variations and Maharashtra, parts of South and North-Eastern India continue to account for the bulk of the fresh cases. Herein lies a paradox. If the serosurvey result of 67 per cent of the population having antibodies is to be a “ray of hope” and an indication of an acquired immunity in large sections of the population, then it would have to be accepted that States with higher incidence of tested numbers at present have a lower-than-average seroprevalence and a more efficient system of testing. In other words, higher numbers today could be signs of relatively greater success in the past in controlling the epidemic and more accurate capturing of the actual spread through testing. To put it differently, some are enjoying the fruits of their failure while others are paying the price of having done relatively better.

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