More than two-thirds of India's population has developed antibodies to fight the coronavirus, according to a nationwide blood serum survey of 29,000 people carried out in June and July.

The fourth national sero survey, included 8,691 children aged 6-17 years for the first time. Half of them turned out to be seropositive which means they had developed antibodies to combat Covid-19.

The survey revealed that 67.6% of adults were seropositive, while more than 62% of adults were unvaccinated.

About 40 crore people of India's 1.4 billion population did not have antibodies and are, therefore, vulnerable to Covid-19, according to the survey.

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"The second wave is still persisting. The danger of new outbreaks is very much there. One out of three Indians is still vulnerable and therefore the pandemic is still not over,"  VK Paul, the government’s top health adviser, said at a news conference.

The study also surveyed 7,252 healthcare workers who are at the forefront in the war on Covid-19 and found 85% had antibodies, while 10% of them were still unvaccinated.

Earlier a sero survey in Mumbai had revealed that 50% of children under 18 had developed antibodies against Covid-19. This had allayed fears among certain sections of the population that children were more vulnerable to Covid-19,

In fact, AIIMS Delhi chief Dr Randeep Guleria has come out in favour of reopening schools in a gradual manner as data shows that children have a high level of immunity to Covid-19. According to him, this would allow children to resume their overall development which has suffered as schools have been shut since March last year.