Sero positivity indicates the presence of antibodies to a certain infection, in this case Covid-19.
Analyzing data of 40,000 patients who tested at their labs across the country, Dr Shah said Thane and Mumbai had overall sero-positive pool of 35% and 30% respectively. The comparative number was 27% in Delhi, 26% in Chennai and 20% in Kolkata. “We conducted these tests between June 26 and August 15. Almost 16,000 were from Mumbai,” Dr Shah said.
Data from other laboratories too had shown similar rates for Mumbai. The BMC’s first sero survey along with TIFR showed that 57% of the people living in slums and 16% in non-slum areas had developed antibodies in July itself. The BMC’s second report is awaited in the next few days. Meanwhile, a closer look at the Metropolis Lab data from Mumbai showed that 44% of those who tested from Parel and Maulana Azad Marg (including parts of Byculla and Mumbai Central) had antibodies. While Borivli had 39% sero-positive rate, the other western suburbs of Saki Naka and Khar had 38% each.
The city’s earlier hotspots — Sion and Worli – had a 39% and 33% rate respectively. Around 35% of the people from Malabar Hill, which has seen a repeated rise in cases over the months, who got tested at the lab, had antibodies. Mulund in eastern Mumbai had a 37% sero-positive rate.
The data showed some surprise as far as the suburbs with least antibody prevalence is concerned: Kandivli had 19% and J B Nagar in Andheri (E) had 18%. The three areas of IIT Bombay, Grant Road and Churchgate had 17% sero-positivity each.
A gender-wise analysis showed that women in the 21-30 age-group and men in the 31-40 age-group had antibodies to Covid-19.
“One salient point was that 80% population showing antibody positivity had a previous history of being diagnosed as Covid-19- positive. However, 20 % of them didn’t have antibodies despite having tested positive for the virus months ago,” Dr Shah said. This could be because they were tested later in the course of the disease or because of variable host immune response.