Two-thirds of Indians have Covid antibodies: Study
The blood serum survey of about 29,000 people in June and July showed 67.6 percent of those tested had antibodies.
The results of the study by the Indian Council of Medical Research (ICMR) show the impact of a devastating surge of cases in April and May, when India reported about 400,000 cases and 4,000 deaths per day.
In December and January, less than 25 percent of those in a similar study had positive antibody tests.
ICMR chief Balram Bhargava said that the study shows "there is a ray of hope".
"But there is no room for complacency. We must maintain Covid-appropriate behaviour," he said in New Delhi on Tuesday.
Only 13 percent of the adults in the study were fully vaccinated.
But a US research group report, also released on Tuesday, estimated that the actual death toll could be up to 10 times higher, citing the number of extra people who died compared with pre-crisis figures.