Coronavirus infections in India passed 1.5 million and deaths neared 35,000 yesterday, but test results in Mumbai slums cast further doubt on official data in the world's second-most populous nation.
The health ministry website yesterday reported almost 50,000 new infections and 768 more deaths.
India now has the third-highest number of cases in the world behind the United States and Brazil, although the official number of deaths in the South Asian nation is far lower.
The South Asian giant, home to some of the world's most crowded cities and where health-care spending per capita is among the world's lowest, passed one million cases only 12 days earlier.
But many experts have said India is not testing enough people, and that many coronavirus-linked deaths are not being recorded as such.
A study released Tuesday that tested for coronavirus antibodies reported some 57 percent of people in Mumbai's teeming slums have had the infection -- far more than official data suggests.
Blood tests on 6,936 randomly selected people conducted by Mumbai's city authorities found that 57 percent of slum-dwellers and 16 percent of non-slum residents had virus antibodies.
Mumbai, where about 40 percent of its 20 million people lives in slums, has reported just over 110,000 infections and more than 6,000 deaths so far.
But deaths in the sprawling slum have not exploded, with local officials saying their aggressive efforts to stem the spread of the virus has been effective.
The survey results suggested asymptomatic infections were "likely to be a high proportion of all infections" and also indicated the virus death rate was likely to be "very low", the study said.
The Mumbai survey came a week after an antibody study commissioned by the government suggested that almost a quarter of people in the capital New Delhi, home to 20 million people, have had the virus.