COVID-19: Serosurvey estimated every fifth person in Chennai infected

Highest infection estimated to be in children, lowest in people more than 60 years

By DTE Staff
Published: Tuesday 01 September 2020
COVID-19: Serosurvey finds every one in five estimated to be infected in Chennai. Photo: Pickpik

Chennai has reported a seropostivity of 21.5 per cent for SARS-CoV-2, according to the results of a serostudy released on September 1, 2020. In other words, one-fifth of Chennai’s population has been estimated to be infected with the novel coronavirus.

While the low seropostivity rate has left a few surprised, what is equally significant is the huge variation in results across 51 wards of the city’s 15 zones. The lowest seropositivity of two per cent has been reported in Ward 32, while the highest of 50 per cent has been reported in Ward 47.













Some 12,405 individuals participated in the exercise. Their samples were collected from July 18-28.

The survey was conducted by the National Institute of Epidemiology, which comes under the Indian Council of Medical Research. It found the Tondiarpet zone had the highest number of estimated infections — 0.29 million. The second-highest number of estimated infections were found in the Teynampet zone. About 0.26 million people were estimated to be infected here.

Children seemed to be the highest infected in Chennai. About 23.8 per cent individuals from the age group of 10-19 years were estimated to be infected. The lowest seroprevalence was in people above 60 years. Only 15.9 per cent of this age group were estimated to have been exposed to the virus.

As opposed to 23.7 per cent females, 19.3 per cent males were infected.

Chennai is the third metropolitan city to report serosurvey results. All eleven districts of Delhi and three wards of Mumbai have been covered by this exercise.

Delhi had reported a seroprevalence of 29 per cent. The variation was in the range of 16.3-31.4 per cent. In Mumbai, it varied hugely between the slum and non-slum populations of the three wards. In slums, where people live in cramped settings, the seroprevalence was reported to be 57 per cent, while it was 16 per cent among the non-slum population.

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