CHENNAI: While the COVID-19 test positivity rate in the city has fallen below 10% according to the Chennai Corporation, it remains higher in neighbouring districts.
The test positivity rate in Chengalpattu is around 16%, said health officials in the district. In Thiruvallur, officials said the positivity rate is 11.5%.
However, the positivity rate in these districts may be slightly higher on paper because of a lag in inter district communication, say sources.
Test positivity rate refers to the percentage of people who tested positive against the total samples tested.
For instance, if a person is technically a resident of Thiruvallur but tests positive and is subsequently admitted for treatment in Chennai, the numbers are immediately reflected in Thiruvallur, say sources.
“However, there is a lag in communicating the number of patients from our district who tested negative in Chennai. Sometimes, it’s not added at all,” said a source.
This means that the number of positive cases (numerator) would include those who tested positive in Chennai but the total number of samples tested (denominator) would not include those who tested negative in Chennai.
“Only if we add that to the number of samples tested within our district itself will we get the exact positivity rate. In that case, it will only be around 10%,” the official said.
According to Thiruvallur health officials, the number of tests in the district has increased.
"On Monday, for instance, we tested 4605 samples. On an average, we test from 3900-4000 samples a day," said a health official.
Officials in Chengalpattu said that the situation was improving in the district.
“We are looking at a downward trend in positivity since last week. We have also increased the number of tests and are testing around 4000 samples a day,” said a Chengalpattu health official.
Chengalpattu recorded 331 new cases on Monday while Thiruvallur recorded 332. A total of 2719 people are under treatment in Chengalpattu and 3409 people are under treatment in Thiruvallur.