A  third of India's population  does not have coronavirus antibodies, which means 40 crore of the population is still vulnerable to COVID-19, ICMR DG Dr Balram Bhargava said on Tuesday while briefing the media on the fourth national serosurvey.

The fourth round of the serosurvey, which examines how many people in a population have been infected with COVID-19 and recovered, was conducted in 70 districts of the country in June-July and included children of 6-17 years of age.

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"We studied 7252 healthcare workers and 10% had not taken the vaccine, the overall seroprevalence in them was 85.2%. In conclusion, 2/3rd of general population i.e above the age of 6 yrs had SARS-CoV-2 infection," Dr Bhargava said, reports news agency ANI

The survey also concluded that there was no difference in seroprevalence in male and female and rural and urban areas. In unvaccinated, the seroprevalence was 62.3% and with one dose of vaccine, it was 81%. In those who receive both doses, it was 89.8%.

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The survey comes on the heels of the deadly second wave of COVID-19 in India that left more than 1 lakh people dead. The wave saw the healthcare system coming under tremendous pressure and hospitals running out of oxygen and medicines.

According to a study by an American research group, India’s death toll from COVID-19 may be up to ten times higher than the official count of nearly 415,000, making the country the world’s worst-affected from the coronavirus.

In a study published on Tuesday, which analysed data from the start of the pandemic to June this year, the Centre for Global Development estimates between 3.4 to 4.7 million people have died from the infection in the country.

In the past one month, many states have revised their COVID toll adding more deaths to the final tally. Among the states are Bihar, Madhya Pradesh, Maharashtra and Rajasthan. Maharashtra, one of the worst-hit states, added 10,000 deaths to its COVID toll on June 11.