More than 70% of people in eight of India’s large states are estimated to have Covid-19 antibodies, a government survey showed on Wednesday, suggesting that a second surge in infections affected many more people than the reported figures.

The survey, which tested a sample of the population for the presence of Covid-19 antibodies, was conducted in June and July and showed that two-thirds of India's 1.3 billion people were likely to have been exposed to the virus. 

The sero-prevalance survey, which tested around 29,000 people across the country, showed that in eight of India's largest and most populous states, more than 70% had antibodies for Covid-19, according to a government statement.

In the central state of Madhya Pradesh, 79% of its estimated population of 70.3 million had antibodies, the survey showed.

At least 75% of the population in the impoverished and densely populated eastern state of Bihar showed the presence of antibodies, as did 71% of the 220 million people in the country's most populous state of Uttar Pradesh, data showed.

India's daily cases have fallen after a devastating second wave that overwhelmed the healthcare system. On Wednesday, it reported 43,654 new cases and 640 deaths, down from a peak of 414,188 daily cases reported on May 7.

India's vaccination has picked up after a lull in April and May, but it may still not be able to meet its stated aim of inoculating all 950 million adults by the end of the year.

As of Wednesday, a total of 440 million Indian adults had received at least one Covid-19 shot, with just over 10% of its eligible population fully vaccinated.