The BMC exercise in wards R North (Dahisar), F North (Sion-Matunga) and M West (Chembur) follows rigorous scientific methods to choose and test residents, while the private laboratories tested anyone who demanded the test. However, both Thyrocare and Suburban Diagnostics laboratories have hundreds of collection centres across the city and have tested almost 12,500 and 10,100 Mumbaikars respectively. About 27.3% of those tested by Thyrocare had antibodies.
Tests show antibodies higher in residents of northern suburbs
The tests by Suburban Diagnostics among Mumbaikars show 24% had antibodies. But a closer look at the Thyrocare data showed interesting contrast within the Mumbai data. Most higher percentage areas were in the northern suburbs as compared to south Mumbai. The main exceptions were Worli—the site of the earliest Covid-19 outbreak —which was second with 41.9% of those tested emerging seropositive, while Chinchbunder had 39.4%.
Vile Parle (E) was at the top with 43% of those tested showing some degree of exposure to the virus, while Goregaon West had 35.6% and Mulund 35.3%. The GPO area was amongst the lowest at 13.2%. Tardeo, another south Mumbai hub, showed 18% positivity.
Thyrocare CEO Dr A Veluswami told TOI both Mumbai and India’s results (24%) show “we are getting closer to 35% positivity when plateauing of cases is known to happen”. The curve takes a downward trend when the figure reaches 45%. “With positivity anywhere between 45%-50%, the virus becomes less impactful,” he added.
Dr Anupa Dixit from Suburban Diagnostics said a look at antibody tests done voluntarily by Mumbaikars had revealed a positive trend. “When we started doing antibody tests in June, we found 18% had antibodies. The figure rose to 20 in a few weeks and has been growing ever since,” she said.
The Suburban Diagnostics chain has conducted 10,100 antibodies tests so far. “We found 24% of those tested had antibodies,” said Dr Dixit. She said 99% of those who underwent the test were asymptomatic and had no indication they had been exposed to Covid-19. “Those who got themselves tested were from the service sector who wanted to rejoin work,” she added. BMC’s first sero survey had showed 57% of those living in slums and 16% of those living in colonies had antibodies. On Friday, AMC Suresh Kakani said the second survey was progressing well. “We have begun sample collection and there is adequate response so far,” he said.