The survey tested blood samples of 21,387 people across Delhi. Among them, 23.48% were found to have Covid-19 antibodies, indicating past exposure to the coronavirus.
The study, conducted by India’s National Center for Disease Control two weeks ago, suggests actual infections in the city are much more widespread than the number of confirmed cases reflects.
As of Wednesday, Delhi has recorded a total of 125,096 cases, accounting for less than 1% of its population of 16.78 million, according to the last census carried out in 2011.
The result of the study, however, suggests that around 4 million Delhi residents could have been infected with the virus by the first week of July.
The coronavirus is still fast spreading in the country, with 37,724 new cases reported in the past 24 hours, bringing the total to more than 1.19 million cases — the third highest in the world after the United States and Brazil.
Delhi reported 1,349 new cases on Tuesday. At least 3,690 people have died of the coronavirus in the city.
In a press release, India’s health ministry said the study indicated that a large number of people infected remained asymptomatic.
“Nearly six months into the epidemic, only 23.48% of the people are affected in Delhi, which has several pockets of dense population,” the ministry said.
“This can be attributed to the proactive efforts taken by the government to prevent the spread of infection,” it said, citing containment measures such as prompt lockdowns and contact tracing.
When India went into lockdown on March 25, Delhi had recorded just 606 cases of Covid-19 and 10 deaths. But the numbers started rising after the city first started easing lockdown restrictions in the third week of May in a bid to resuscitate its economy. By June 8, it had more than 40,000 cases.
Other cities around the world have conducted similar antibody studies in the past, but the figures in their results are much lower than Delhi’s 23.48%.