India, Sept. 17 -- The prevalence of antibodies for Covid-19 rose from 29.1% to roughly 33% between August and September, according to the initial findings of the serological survey in Delhi, senior officials in the Capital's administration said on Wednesday.

The number represents the proportion of people from among 17,000 who were sampled, though the final figures are yet to be officially released. If extrapolated to the roughly 20 million population, the finding implies 6.5 million people may now have been silently exposed to the virus, more than 33 times the 193,526 confirmed infections till September 7 (the date on which the 7-day sampling ended).

"The report has been submitted to the health department and it is currently being revi...