The Indian Council of Medical Research (ICMR) has completed the second round of sero survey, to determine the prevalence of coronavirus disease (Covid-19) in the country, and is analysing the final phase of results, the council announced on Sunday.
“The second round of countrywide sero survey led by ICMR has been successfully completed. The final phase analysis of the survey is now underway and will offer a comparison with the results of the first survey,” it said in a statement.
Sero survey is done by analysing blood samples of selected individuals for antibodies against Sars-Cov-2, the virus that causes Covid-19. It determines if a person has already been infected and recovered, considering a majority of patients do not exhibit symptoms and not everyone is getting tested for the viral infection.
According to sources at ICMR, the final result of the sero survey is expected to be made public by the end of the month.
The sero survey also aims to determine how the disease prevalence has changed since the first sero survey in May, when the nationwide lockdown was in force, to now, post-lockdown with fewer restrictions on public movement.
Close to 24,000 samples have been tested across the same 69 districts in 21 states that were covered in the first round of the national sero survey.
ICMR’s National Institute of Epidemiology in Chennai (Tamil Nadu) is the nodal agency supervising the survey and analysing results.
Director general ICMR, Dr Balram Bhargava, had also confirmed recently that the sero survey was already complete and the results were likely going to be out by the end of September.
Like the previous survey, this survey was also designed as a cross-sectional survey of adults aged 18 years or above from 21 states, wherein the districts were categorised into four strata according to the reported Covid-19 cases per million population (zero, low: 0.1-4.7, medium: 4.8-10 and high: >10).
The first sero survey, which was conducted by ICMR along with National Centre for Disease Control, state health departments and World Health Organization (WHO), had shown the pan-India prevalence of Sars-Cov-2 to be 0.73%.