Covid-19: Kolkata learns from Delhi mistake, to have RT-PCR follow-up tests – Times of India

Kolkata News
KOLKATA: The health department has started ramping up the number of rapid antigen tests (RAT) that now account for about 50% of the Covid tests conducted in the state daily. But taking a lesson from Delhi, which came under the scanner for relying on RAT tests with health experts fearing suppression in the number of positive cases, state health officials say they were re-checking negative samples of each symptomatic patient to ensure that not a single case is missed out.
Though the Indian Council of Medical Research (ICMR) approved RAT for containment zones and hospital settings on June 14, Bengal started using RAT kits only on July 28 with 1,183 tests out of the 10,000 kits it had procured in the first lot. These were distributed mostly among hospitals to use them on patients who needed immediate diagnosis. RAT takes just about 30 minutes to throw up a result in comparison to six to eight hours by RT-PCR, which is regarded as the gold standard for Covid tests.

But the number of RAT tests shot up majorly in August. Out of the total 9,13,460 tests done in the month, 4,01,402 were RAT. “At present, the ratio of RAT and RT-PCR tests in the state is 50:50. But the health department is taking all steps to re-confirm negative cases of symptomatic patients by RT-PCR so that we don’t miss out positive cases,” said Pradip Mitra, former director (medical education), who is now the coordinator of Bengal’s Covid management and containment committee.
The number of RAT in the first four days of September was 92,150 against 86,619 RT-PCR tests. The state government has already procured 10,000 lakh RAT kits and is on the way of procuring more.
“RAT kits are useful in cases where results are required immediately. While a positive sample is to be taken as positive, negative samples, especially those of symptomatic and highly suspicious cases, need reconfirmation by RT-PCR,” said Pratip Kundu, director of the School of Tropical Medicine, Kolkata.
Health care experts said that while a testing strategy combining RT-PCR and RAT was a good decision, they warn that RAT should be restricted to containment zones and specific cases.
“Meticulous use of RAT, especially in containment areas and on highly suspicious patients like that of SARI (severe acute respiratory illness) and ILI (influenza-like illness) could prove useful in containment strategy. But deploying RAT for mass screening is debatable because the chance of kits throwing up negative results in asymptomatic patients is high,” said Debkishore Gupta, infectious disease control specialist.
Currently, some civic bodies, including KMC, is using RAT to test residents of housing complexes. Health department officials claim that history of each patient who is tested by RAT is taken to mark if it is a case of a highly suspected Covid patient. And if the result of such a patient is negative, the person’s sample being tested by RT-PCR again.
“Along with RAT, we have also ramped up RT-PCR tests. The number of testing labs has gone up to 71. We will be scaling up the number of RT-PCR labs further,” said a senior health department official.