Positivity rate highest in Chennai – The Hindu

Tamil Nadu’s positivity rate, or the number of samples that test positive among the total figure, is between below 1% and 20%, with the higher percentile in high-incidence centres such as Chennai, at 23.2%. Data analysed by scientists at the National Institute of Epidemiology (a unit of the Indian Council of Medical Research), shared on Twitter on Saturday, showed that the highest positivity rate went just over 20% in the State.

The institute’s deputy director, Prabhdeep Kaur, tweeted that the team working on coronaupdates.in looked at the June 20 medical bulletin issued by the Health Department to calculate the positivity rate and plot it on a map. Chennai topped the list, but was followed by neighbours Chengalpattu (18.1%) and Tiruvallur (17.3%), where the number of cases has been steadily rising.

A bulk of the districts — 18 of them — are in the 1%-5% category, and this is followed by 12 districts in the below 1% category. Four districts fall in the 5%-10% category. Testing data for districts was shared by the Health Department only on June 20, and it has yielded interesting data on cumulative trends. It underlines the request made by many, including Madurai MLA PTR Palanivel Thiagarajan, to share district-level testing data on a daily/weekly basis.

“At one point, the positivity rate in Chennai was about 35%. This seems to have dropped,” said P. Kuganantham, former Chennai Corporation health officer. “In fact, since then, despite increased testing, which is also focused among symptomatic patients and high-risk groups, it is time to ask if the infectivity rate is on a downward swing,” he said. Corporation Commissioner G. Prakash has also claimed that the positivity rate has shown a downward swing from 35% in the city.

Measures that might have possibly worked are the increased testing of symptomatic persons in all areas, focusing attention on those with symptoms and contacts of patients, and the fever camps that are being held, he said. In Chennai, house-to-house surveys, especially in the red zones, have helped identify the vulnerable, he said. “This should continue throughout July, even after the lockdown is lifted. We need the public to be disciplined even when the lockdown ends.”