Positivity rate is the percentage of positive cases from the total samples tested. According to WHO guidelines, recommended positivity rate for COVID is 5%.
According to TN’s COVID resource centre data, until June 20, Chengalpattu had a positivity rate of 18%, Tiruvallur above 15% and Kancheepuram over 10%. Other districts with positivity rate between 5-10% include Tirunelveli, Ariyalur, Tiruvannamalai, Cuddalore, Salem and Tiruvarur. Vellore, Ranipet, Karur, Thoothukudi, Villupuram, Perambalur, Madurai, Virudhunagar, Dindigul and Ramanathapuram have positivity rate between 1 and 4% while the remaining districts have a positivity rate of 1% or less.
Experts say that a high rate of positivity indicates that only the sick and close contacts are tested while the virus could have already spread to many. More testing has to be done in areas with high positivity rates to ensure that the virus is contained, according to virologists.
Director of Public Health and Preventive Medicine Dr TS Selvavinayagam says TN has done maximum tests pan India. “We have crossed over a million tests. If needed, we will test more people,” he said. “Most districts were testing adequately as on June 20. Places that witnessed spike need to increase testing to reduce infection. While testing of samples has improved in most districts, many are witnessing an upward trend. If the testing and tracing is scaled up, the infection can be contained,” said Dr Prabhdeep Kaur, deputy director at National Institute of Epidemiology.