While the survey indicated that less than 1% of the adult population was exposed to the new coronavirus in mid-May 2020, the official count at that time was even lower with only 85,940 cases detected as of May 15. This would indicate that the majority of cases may occur during the first months of the outbreak in the country.
This could be because the testing strategy was then adapted to limited test kits and laboratory capacity and also because a significant number of infections may have been asymptomatic. A serological survey estimates the percentage of the population exposed to a virus by finding the presence of antibodies. Antibodies indicate that a person has been infected but is no longer infected.
Although the ICMR had shared some study findings in June, the final study was published in the Indian Journal of Medical Research on Friday. A total of 30,283 households were visited and 28,000 people registered for the sero survey nationwide. Also in June, the ICMR had estimated the prevalence of infection at 0.73%. It had also said that the risk of spread was 1.09 times higher in urban areas compared to rural areas. While in urban slums, it was 1.89 times higher than in rural areas.
“Men, living in urban slums and an occupation with high risk of exposure to potentially infected people were associated with seropositivity,” the study said.
Of the 157 people who were positive in the survey, 43.3% belonged to the age group of 18 to 45 years, 39.5% were 46 to 60 years and the remaining 17.2% were over 60 years . However, seropositivity was higher in the 46 years. -60 years, with 62 of 9,525, or 0.65%, testing positive and the lowest in the youngest age group with 0.5% (68 of 13,552).
“The IFR (infection mortality rate) in the surveyed districts of the upper stratum, where the notification of deaths was strongest, was 11.72 to 15.04 per 10,000 adults, using May 24 and May 1. June 2020 as plausible benchmarks for reported deaths, “the study said.
The survey divided the districts into four strata, and interestingly, 8,56,062 infections occurred in districts without cases. At the time of the survey, there were 233 districts without cases in India.
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