MUMBAI: Results of the fifth sero survey in Mumbai, which will be released in the next few days, suggest that the city may be close to herd immunity against Covid-19, said BMC sources.
“Around 70% to 80% of those surveyed in the city’s 24 civic wards in August had antibodies to Covid-19,’’ said an official who didn’t want to be named. The city has also administered at least one dose to 82% of the 93.48 lakh eligible population.
However, sero surveys are not fool-proof: a survey in Delhi had indicated that 60% of citizens had antibodies to the virus but the capital was among the worst hit during the second wave with 25,000 cases reported daily. “If a survey is not done scientifically by choosing people in a randomized manner, it may not be very indicative of the ground realities,’’ said a doctor.
BMC additional commissioner Suresh Kakani refused to confirm the numbers. “We are fine-tuning the findings of the fifth sero survey report and will release it in a day or two,’’ he said. The BMC administration is still worried that people will become lax about Covid-appropriate behavior such as wearing a mask or maintaining social distance. “If a new variant emerges, then everyone could be vulnerable to Covid,’’ said the doctor.
The fifth survey was done during the lockdown, in the second week of August—ahead of the rising curve noticeable in the last 15 days in the city. The fourth survey among the pediatric population showed 50% of children tested had antibodies to the virus. The third survey across 24 civic wards in February-March showed 41% in slums and 28.5% in non-slum areas had antibodies. The first two surveys were in three wards; the exposure was found to be 45% in slums and 18% in buildings during the second survey in August 2020, and 57% and 16% respectively during the first survey in July 2020.
