India could be witnessing a much wider spread of coronavirus infections and the rate of contagion may be a lot higher in most-affected cities such as Delhi, Mumbai, and Pune, according to reports based on a critical serological survey conducted by the Indian Council of Medical Research (ICMR) across 69 districts. The survey report is likely to be made public early next week. The survey will help understand the prevalence of Covid-19 infection in India’s population and, thus, also impact the country’s unlocking strategies. The preliminary findings from the survey were shared with the Union Cabinet secretary and also the Prime Minister’s Office.
- The serological (blood) test detects the presence of coronavirus antibodies in a person and indicates whether he/she had contracted the virus. It is especially helpful in understanding the spread among asymptomatic people.
- Some media reports suggested that in several containment zones in high-prevalence districts, 15-30 per cent of the residents could be exposed to the virus.
- Many of them may have quietly recovered. A senior scientist in the ICMR said the findings will be made public once the data from all the districts is collected.
- The Amphan-hit West Bengal could not send its data earlier. We will make the report public once we are able to analyse the entire dataset. It can be out early next week,” he said. The data from at least seven or eight districts is yet to be analysed.
- A public health expert from Ahmedabad said while India has not officially accepted it is witnessing community transmission, the infection, at least, is in the local-transmission mode.
- The serosurvey will show the extent of infection among asymptomatic people. The RT-PCR testing of symptomatic people is only the tip of the iceberg, as most people are asymptomatic.
- As of June 2, more than 34,000 individuals had been tested as part of the survey. Samples were collected from 10 hotspot cities — Mumbai, Thane, Pune, Ahmedabad, Surat, Delhi, Kolkata, Indore, Jaipur, and Chennai.
- The ELISA test developed by the Pune-based National Institute of Virology having higher levels of accuracy is being used for the survey.
- In a serosurvey, blood samples of people are collected to test for the presence of antibodies specific to a pathogen.
- In this case, it was meant to test for IgG antibodies against SARS-CoV-2 that normally appear 14 days after the infection and continue to be present in the blood serum for months.
- The ICMR, with help from the National Centre for Disease Control, World Health Organisation's India office and the state governments had collected nearly 24,000 samples from 70 districts in the country from randomly picked individuals.