Two-thirds of Indians have Covid antibodies, government study shows

An estimated two-thirds of people in India have Covid-19 antibodies, according to a new government survey that has raised hopes that the worst of the country’s pandemic crisis is over, despite a sluggish vaccination campaign.

The survey of more than 36,000 people in 70 districts across 21 Indian states found that 62 per cent of unvaccinated Indians had antibodies indicating past exposure to the virus.

The so-called seroprevalence study was carried out by the Indian Council of Medical Research in the last 10 days of June and the first week of July, just as a devastating second wave of Covid-19 infections was receding. Overall, more than two-thirds of Indians have antibodies, it concluded, either acquired from the vaccination campaign or past infection.

India has fully vaccinated just 6.5 per cent of its population, while about a quarter of the population has received at least one dose.

The ICMR figures appear to confirm what epidemiologists have long claimed: that India’s official coronavirus statistics — 31m confirmed infections since the start of the pandemic — vastly understate the true spread of the virus in the country.

Seroprevalence levels were highest — at about 77 per cent — in people over the age of 45, the group that received first priority access to vaccines. Seroprevalence among children aged six to nine was 57 per cent, while 61 per cent of those age 10 to 18 had antibodies. People under 18 are not yet eligible for vaccination in India.

Experts said the survey affirmed how far the virus had spread during India’s ferocious second wave earlier this year. But they cautioned that another surge in infections could not be ruled out, while a third of India’s 1.4bn people still lacked antibodies.

“Given the transmissibility of the Delta variant, we are still susceptible to a third wave,” said Brian Wahl, a New Delhi-based epidemiologist at Johns Hopkins Bloomberg School of Public Health. “Even that high level of seroprevalence is still probably below what a herd immunity threshold might look like for the Delta variant.”

Chandrakant Lahariya, a public health expert, said that any third wave was likely to be smaller than the onslaught of cases that overwhelmed India’s health system in April and May. 

“Localised smaller waves are possible in [geographical] pockets where seroprevalence is low in the months to follow,” he added.

Officially India has recorded just 414,000 Covid-19 deaths since the virus was first detected in the country in early 2020. The Indian government counts only patients who die in hospital with a positive test as Covid-19 deaths, excluding large numbers of victims who could not obtain tests or hospital care, or who died from coronavirus-related complications after being discharged.

A second study, also published on Tuesday, estimated that India had suffered between 3.4m and 4.7m excess deaths during the pandemic, about 10 times the official death toll.

The study, whose three authors included Arvind Subramanian, the government’s former chief economic adviser, examined three sources of data: all-cause mortality statistics from seven large states; seroprevalence studies; and household surveys carried out by the Centre for Monitoring Indian Economy.

While each of the three sources yielded different estimates, the paper’s authors said “they all point to significantly greater deaths than the official estimates” and indicated that India’s “first wave was more lethal than is widely believed”.

“What is tragically clear is that too many people, in the millions rather than the hundreds of thousands, may have died,” the authors said.