The Delhi government has been regularly conducting antibody tests since August 2020 to assess the spread of the virus in the capital region. In the fifth and the largest survey so far, more than 28,000 samples were tested across 11 districts in Delhi between Jan. 11 and Jan. 22.
Preliminary results show that more than 60% of residents in one district in Delhi had antibodies against the coronavirus. The antibody rate in other districts more than 50%. If these findings hold true, it would imply that half of the city's 20 million people has been exposed to the virus and recovered.
Researchers believe that if 60% or more of the population develops antibodies against the coronavirus, there is a significant likelihood of achieving herd immunity. While herd immunity may help slow the spread of the virus in Delhi, it comes at a terrible price. More than 10 million people in India have contracted coronavirus and more than 154,000 have died. Delhi alone has seen more than 634,000 cases and more than 10,000 deaths, according to Johns Hopkins University.
Experts believe the city is nearing heard immunity because of the inability of the urban population to comply with lockdown restrictions and social distancing norms. Some believe the antibody rate in the city may increase to 70% in the coming months, party aided by vaccination.
Speaking to The Indian Express, Neeraj Nischal, MD< an associate professor at the All India Institute of Medical Sciences in New Delhi, said: “It shows that a lot of asymptomatic infections did happen in the course of the pandemic, which were not reported at that time. This is our natural way of acquiring herd immunity as approximately 50% have developed antibodies against the virus."
Another sign the area is reaching herd immunity is the rapidly declining COVID-19 positivity rate, which currently stands at about 0.3 per cent. From more than 7,000 daily cases at the peak in November 2020, Delhi is now recording fewer than 200 cases per day.