India had 6.4 million patients with coronavirus disease (Covid-19) in early May when samples were collected for the Indian Council for Medical Research (ICMR) first national sero-survey to detect the prevalence of viral disease, according to the findings that were published three months after the results were first made public in June.
In percentage, the national prevalence was found to be 0.73%. The most affected were those between the age group of 18 and 45 years, since 43.3% had developed antibodies against SARS-CoV-2, which causes Covid-19.
While the patients with Covid-19 in the age group between 46 and 60 years represented 39.5% of the individuals sampled.
In total, 30,283 households were surveyed and 28,000 people had signed up for the study.
“Population-weighted seroprevalence after adjusting for test performance was 0.73%. Men, who lived in urban slums and were at high risk of exposure to potentially infected people, were associated with seropositivity. A cumulative 6,468,388 adult infections were estimated in India as of early May, ”the findings said.
A total of 151 (0.5%) people reported a history of contact with a Covid-19 patient and 70 (0.3%) reported that they were tested for viral infection prior to the survey.
From May 11 to June 4, a random sample community survey was conducted in 700 villages and districts, which were selected from 70 districts in 21 states across the country.
The samples were classified into four strata according to the incidence of reported Covid-19 cases.
The survey had enrolled 400 adults per district of 10 clusters and one adult per household. Serum samples were tested for immunoglobulin G (IgG), a type of long-acting antibody, using the Kavach Covid-19 ELISA detection kit.
The seroprevalence ranged between 0.62 and 1.03% in the four strata of these districts.
The published article shows that IgG antibodies against viral infection begin to appear at the end of the first week after symptom onset and most cases are IgG positive by the end of the second week, according to the researchers.
The findings were published in the Indian Journal of Medical Research (IJMR).
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