15 per cent population may have virus antibodies, says private lab data
A new analysis by a private laboratory has indicated that nearly 15% of the country’s population may have developed antibodies against SARS-CoV-2.
Thyrocare, a private diagnostic laboratory shared data from 60,000 antibody tests across 600 pincodes that it conducted over 20 days. Of those 15% tested positive for antibodies.
Dr A Velumani, Promoter, Chairman, Managing Director and CEO of Thyrocare had tweeted on July 17 that 180 million Indians may have been already silently immunised in India. “Too good to believe. Hope kits do not have high false positives.”
According to Thyrocare’s data the highest positivity rate for the antibody test is in Bhiwandi, Thane at 47.1% . The lowest positivity rate was found to be in Alibag in Maharashtra at 0.7%.
Thyrocare used Elisa (enzyme-linked immunosorbent assay) and Chemiluminescence immunoassay (CLIA) antibody tests to arrive at the findings.
Independent experts said the findings cannot be generalised. According to the ICMR’s (Indian Council of Medical Research) antibody testing survey, less than 1% of the population – 0.73%--in non-containment zone districts was found to have contracted Covid 19. That was conducted in mid-May.
Interestingly, the Thyrocare findings are in sync with the results of an antibody testing survey in Delhi that were released Tuesday and showed that 22.86% of the population has been exposed to SARS-CoV-2.
“Its good that a private laboratory has conducted as many as 60,000 antibody tests. ICMR had conducted around 20,000. However, the numbers are too low to generalise. I don’t know if most representative areas are covered and population heterogeneity is also a factor,” said Amit Singh, associate professor, Centre for Infectious Disease Research, IISc, Bengaluru.
“From the list of areas it appears that the focus has been urban or semi-urban areas. We cannot generalise the findings for rural areas. Johns Hopkins says 70% of the population should grow antibodies for herd immunity. So what is the significance of these findings?” asked Dr Shobha Broor, former head, microbiology department, AIIMS, Delhi.
“We considered random tests conducted between June 28 and July 19 in only those areas where we have conducted at least 50 tests. I have shared the data with ICMR. By July 30, I expect to do 1.2 lakh tests which will give us a clearer picture,” said Velumani.