Among 11 States Madhya Pradesh Has Highest Seroprevalence Against Covid And Kerala Has Lowest: ICMR Serosurvey

The latest findings of a serosurvey conducted by the Indian Council of Medical Research (ICMR) between 14 June and 6 July has shown that at least two-thirds of the population surveyed in 11 states in India had developed antibodies against Covid-19, and with 79 per cent seroprevalence, Madhya Pradesh tops the list.

The Union Health Ministry published the results of the fourth round of countrywide serosurvey conducted by the ICMR, involving 70 districts in India, on 28 July. Apart from Madhya Pradesh, this study also revealed that seroprevalence was found to be 76.2 per cent in Rajasthan, 75.9 per cent in Bihar, 75.3 per cent in Gujarat, 74.6 per cent in Chhattisgarh, 73.1 per cent in Uttarakhand, 71 per cent in Uttar Pradesh, 70.2 per cent in Andhra Pradesh, 69.8 per cent in Karnataka, 69.2 per cent in Tamil Nadu and 68.1 per cent in Odisha.

In Assam and Maharashtra, the seroprevalence is found to be 50.3 and 58 per cent, respectively, while in Kerala, it is 44.4 per cent, which placed the South Indian state at the bottom of the list.

The Health Ministry has recommended states and union territories to conduct their own seroprevalence studies in cooperation with the ICMR to ensure that they follow a standardised approach. The results of such studies can therefore be used by governments to drive an objective, transparent and evidence-based public health response to the pandemic rapidly.

According to a statement from the Ministry, the ICMR's countrywide serosurvey was aimed to determine the amount of novel coronavirus infection across the country. It added that "therefore, the national serosurvey results do not reflect the heterogeneity of seroprevalence between districts and even between states".

Earlier, a paediatric serosurvey conducted in Maharashtra's Mumbai has revealed that 51.18 per cent of the children under the age of 18 have antibodies against the SARS-CoV-2 caused disease. As reported, the findings were revealed after the civic body-run BYL Nair Hospital and Kasturba Molecular Diagnostic Laboratory (KMDL) performed the survey from 1 April to 15 June.

A serosurvey involves testing a group of individual's blood serum in order to track trends in the prevalence of the SARS-CoV-2 infection at the district level. The ICMR and the National Centre for Disease Control decided to conduct the surveillance in partnership with key stakeholders and state health departments.

In addition to routine testing, a more focused population-based serosurvey of high and low-risk groups is conducted in select districts. Not only would this aid the government and its agencies in monitoring Covid-19 trends, but it will also allow them to check for community transmission if there is any.

However, for such surveys, the agencies use a combination of RT-PCR and Elisa antibody kits (enzyme-linked immunosorbent assay). Throat and nasal swabs are collected for RT-PCR tests, and 25 samples go for testing at a time. Blood samples are collected in addition to RT-PCR tests to detect IgG antibodies for Elisa testing. In subsequent rounds, IgG Elisa-based serum sample testing replace RT-PCR-based testing for surveillance purposes.

The Elisa testing kit, which has been developed by the National Institute of Virology and Zydus Cadila, is said to have a specificity of 97 per cent and sensitivity of 92 per cent.