Covid-19: Faulty kits cast doubt on positivity rate drop

PUNE: Doctors at Sassoon were among the first to suspect something was wrong.
Over a week ago, the Covid test positivity rate at the hospital suddenly dropped from 22% to 9%. The value’s abrupt fall raised red flags.

Their suspicions were confirmed this week when it was revealed the state has recalled nearly two lakh RT-PCR testing kits, purchased from a Kolkata-based company, for being “faulty”.
These kits, mainly deployed at government labs, were generating a high number of false negatives. It’s believed they may have been used to test at least 25,000 samples.
Healthcare activists now suspect these machines may have caused the recent dip in Pune Metropolitan Region's positivity rate.
Nearly 40% of all RT-PCR tests are carried out at 58 public labs in the state. In PMR too, much of RT-PCR testing is done at government labs.
“Authorities should find out if the drop in positivity rates in the PMR was because of these faulty kits,” said activist Abhijit More.
TP Lahane, head of the state directorate of medical education and research, said, “These faulty kits were used only for three days at some state labs, mainly between October 8 and 10. Their use was immediately stopped.”
Lahane denied the kits had caused the drop in test positivity rate. “After doctors in Nanded, Miraj, Jalana and Pune reported sudden drops at their centres, we asked them to retest samples using kits distributed by the National Institute of Virology. So every false negative was retested by the NIV kit.” However, a doctor at Sassoon hospital said the negative results were not retested using the NIV kits.
Pune divisional Commissioner Saurabh Rao said a probe is on. “We are checking how many kits were used in PMR. This report will help us decide on re-testing.” He added the Kolkata-based supplier has been blacklisted.
Sanjeev Wavare, assistant medical officer of health with the PMC, said, “A total of 5,000 tests are done in PMC limits daily — 2,000 are carried out at government labs. Sassoon does 500-700 tests daily and the NIV does 1,300 to 1,500. Sassoon uses kits procured by the state government, but the NIV uses kits procured by the central government."
“After the kits were found faulty, Sassoon has started using NIV kits. We will investigate whether those who tested negative via the faulty kits were retested using the NIV kits or not,” Wavare said.