Mumbai: In addition to the tests being performed to detect Covid-19, the state health department has also put in use TrueNat, an instant testing facility, which the authorities have been using for diagnosing TB.
The officials said that since May, over 26,215 persons have undergone the TrueNat test and of these around 7,693 were found positive in the first step, which amounts to nearly 30 per cent. However, in the second step of the test, which is mandatory to confirm the reports of an individual, the numbers have gone down and only 20 per cent have tested positive.
Dr Pradip Awate, state surveillance officer said currently they have limited their TrueNat tests compared to RT-PCR and Antigen testing, but they are planning to increase further as it gives results in 20 minutes.
“The guidelines issued by the Indian Council of Medical Research (ICMR) in May stated if the E-gene screening is negative, the sample will be considered as true negative. But if the sample is positive, the RNA dependent-RNA polymerase (RdRp) assay will be done as a confirmatory test. If the sample tests positive, it will be considered as true positive and no further test will be required,” he said.
The TrueNat is a chip-based real-time polymerase chain reaction (RT-PCR) test kit. Earlier, it was only being used as a screening test for TB patients. According to ICMR, the diagnostic tool involves two steps — E gene screening assay for the suspected Covid-19 samples followed by a confirmatory assay of RdRp enzyme found in the virus RNA. TrueNat is an indigenously developed, portable version of CB-NAAT or cartridge based nucleic acid amplification test, also known as the Genexpert test. The advantage of this test is that it is quick and portable. The TrueNat machines were also used for detecting the Nipah virus outbreak in Kerala.
Suresh Kakani, Additional Municipal Commissioner, BMC said TrueNAt tests are cheaper and affordable which do not run on battery unlike CB-NAAT. “We have also done 2 per cent of TrueNAt test of the overall testing, of which 2-3 per cent of them have shown the presence of E-gene. We are now also planning to use this TrueNAt in containment zones and slums for testing,” he said.
Recently, the Maharashtra government issued fresh guidelines for Covid-19 and they are now planning to conduct TrueNat tests for those requiring emergency operations, pregnant women and persons brought dead to hospitals. Moreover they are also planning to conduct TrueNat tests on dead bodies in case the doctors have suspension of Covid-19 infection.
Health experts said it is a good move by the state government which helps to detect the virus within 20 minutes compared to RT-PCR which takes 8 hours to give results and until that time patients have to wait to know what is their result. “Early detection and diagnosis will save more lives and time of patients and will also help the doctors given immediate treatment. However there is a need for more study to know the accuracy of the TrueNat test,” he said.