New Delhi has reported one of the highest rates of coronavirus infection of any major city, surpassing a figure recorded in New York as nearly a quarter of people in the Indian capital show signs of an immune response. Some 23.5 percent of people had IgG antibodies that indicate past exposure to the virus in blood tests carried out randomly selected Delhi residents, according to government data. Many have not displayed obvious symptoms. The figure exceeds the 22.7 percent rate recorded in New York City – a previous high for urban infections – in a study in April by NY State Department of Health and NYState University at Albany.
Danny Altmann, professor of immunology at Imperial College London, said that of the cities reporting population-wide data on antibody levels “this figure from New Delhi is at the higher end, suggesting there may have been wider exposure and less effective distancing.” The data indicates that the spread of the virus in India’s big cities is more widespread than Narendra Modi’s government has been willing to acknowledge.
It was based on a survey of 21,387 Delhi residents from June 27 to July 10 and released by the Ministry of Health and Family Welfare this week. Professor Altmann noted that Delhi’s infection level is far below the 60 percent believed to be needed for herd immunity, “even if one were to assume durability of natural antibodies, which now looks less likely”. But some experts said the results were still good news as they indicated that the city’s residents may be inching closer to a level at which it becomes more difficult for the virus to spread at a rapid rate.
The latest figures for London suggest that only 15 percent of the population has developed antibodies to protect against Covid-19, while only one in 10 have in Geneva and Madrid. Studies in Tokyo have suggested as low as 4 percent of the population has developed antibodies.
Preliminary results from a study in the Amazonian city of Iquitos in Peru, which has a population of less than half a million, have suggested antibodies could be present in 71 per cent of residents.