More than a quarter of Indian children aged between 10 and 17 may have already contracted COVID-19, according to a government serological survey released on Thursday, higher than the 21.5% of the overall population found to have been infected. “The overall picture still shows that more than 75 per cent of the population even now can get infected,” said Vinod Kumar Paul, who heads a government group of experts on vaccine strategy, urging people to keep maintaining social distancing and wearing masks. The national survey, however, suggests that more than 290 million people may have already been infected in the country.

The survey of more than 35,700 people above 10, conducted in the last two months, gave a much lower estimate for the average number of people to have contracted COVID-19 than other research. Separate tests done on more than 700,000 people across India by diagnostics company Thyrocare Technologies showed 55% of the country’s 1.35 billion people may have already been infected, its chief told Reuters last week. India has officially reported 10.8 million infections, the world’s highest after the United States, though its cases have come down sharply since a mid-September peak of nearly 100,000.

Among 7,171 randomly-tested healthcare workers, 25.7% were found to have developed antibodies. The Delhi government had said this week that it was approaching herd immunity through natural infection as 56 per cent of its residents had COVID-19 antibodies. The government also said nearly 46 per cent of the country’s 9.6 million registered healthcare workers had been given the first vaccine dose since an inoculation campaign began on January 16.