CHENNAI: RT-PCR clinical tests likely detected only 1.4 per cent of SARS-CoV-2 cases in Madurai district during the first COVID wave, showed a study published in Lancet, a medical journal.
The study published on Friday also pointed out that likely only 11 per cent of deaths among individuals aged 15 years and older were reported. Thus, showing that the districts missed a large number of infections and deaths.
Led by epidemiologist Ramanan Laxminarayan, Princeton University, the authors, including some TN government officials, analysed the RT-PCR test data between May 20, 2020 and October 31, 2020 and also sero-prevalance surveillance testing conducted from October 13, 2020 to November 5, 2020 in Madurai district.
The study aimed to assess predictors of infection and mortality within an active surveillance study, and to probe the completeness of case and mortality surveillance. The study said that Madurai district conducted 13.5 diagnostic tests per 100 inhabitants as compared to the 7.9 tests per 100 inhabitants throughout India.
From a total of 4,40,253 RT-PCR tests done in Madurai district, 15,781 (3.6 per cent) SARS-CoV-2 infections were identified with 5.4 per cent of them being positive among individuals with symptoms and 2.5 per cent of them being positive among individuals without symptoms.
Seroprevalence was 40.1 per cent at age 15 years or older by the end of the study period, indicating that RT-PCR clinical testing and surveillance testing identified only 1.4 per cent of all infections in this age group.
"Higher risk of mortality among patients in Madurai than those in the USA, Europe, China and South Korea, suggesting surveillance in Madurai captured a more severe clinical spectrum of cases," the study observed.