Understanding TrueNat: Reliability and process involved in testing Covid-19

Purnungba Longkumer
Dimapur, June 12 (EMN): After the Indian Council of Medical Research (ICMR) approved the use of TrueNat diagnostic machine, used for testing drug-resistant tuberculosis (TB), for conducting novel coronavirus (Covid-19) tests, the Health department of Nagaland has purchased several machines in an effort to ramp up the testing capacity in the state.

Speaking to Eastern Mirror, district tuberculosis officer in Mon district, Dr. Tinenlo James, informed that the machine they were using is a CB-NAAT (Cartridge-Based Nucleic Acid Amplification Test) used to diagnose modality for tuberculosis and resistance to the drug, rifampicin (Rif).

James informed that the TrueNat machine is used to diagnose TB in a rural setup, as it is portable as well as chargeable with a power backup up to eight hours.

When asked about the reliability of the TrueNat machine for testing Covid-19 cases, he informed that according to Molbio Diagnostic Pvt. Ltd., the manufacturing company, the specificity and sensitivity is 100%.

James informed that according to the guidelines, all samples of suspected Covid-19 cases should be first tested by the ‘e-gene screening assay’ and all negatives are to be considered as ‘true negatives’. However, positive samples should be subjected to confirmation by another step, which is RNA-dependent RNA polymerase (RdRP) gene confirmatory assay, and the samples that test positive by this assay must be considered as ‘true positive’.

He also added that the TrueNat machine can do the second test for the confirmation of positive cases but to process the second test, they need a special test chip but ‘the company provider of the chip are unable to supply it as of now’.

“Once RdRp chip is made available by the supplier, the second test can be processed by the TrueNat machine itself and it would be much easier to get confirmation of positive cases within a short period of time,” he said.

The distributer informed that RdRp chips would be provided within 10 to 12 days; so for now, confirmations of second tests are being sent to ICMR Dibrugarh, the doctor said.

The TrueNat machines consist of uno (single), dou (double) and quattro (four) slots where the chip is inserted to get the result. As of now, Mon district has two TrueNat machines with one single slot and another machine with double slot.

James also informed that various pathogens can be diagnosed through TrueNat machine like HIV, hepatitis B, malaria, falciparum, dengue and chikungunya etc., and they all require specific chip to diagnosis the particular disease.

When queried about the time taken for the test results, he informed that it all depends on the workmanship of the lab technicians and added that once they load the cartridges in the TrueNat machine and extract the RNA and test it; the result will come out within 40 to 45 minutes.

The whole process, including collecting the swab samples from the patients would take around 1:15 minutes for a single patient test.

Once the sample is collected and brought to the lab, even one person can handle the TrueNat machine since qualified lab technicians, who have been working on other laboratory activities, have been trained so that they can handle it easily, he said.

When asked about the advantages of TrueNat machine, he informed that it is portable and the testing time is drastically reduced. It can be used even in field setting and the biohazard is very minimal compared to other Covid-19 testing laboratories.

He added that it does not require constant electricity and a sophisticated lab but the only thing is that they have to be very careful while collecting the samples with proper equipment. He added that the ‘only problem as of now is that for confirmation of positive case, we have to send it for RT-CPR test but when the special chips for the second test is made available, the TrueNat machine would be full of advantages’.

When queried about the cost for testing samples through TrueNat machine, he informed that, including all the testing kits procured by the government, it would cost around INR 1059 for one sample test.

However, when the machine and all the testing kits are bought through private sector, it would range around INR 1500 per test, and for RT-CPR test for confirmation of positive case, the charge would be different, he added.