Is RT-PCR machine reliable?

Monday Musing

[ Amar Sangno ]
Going by data from the Covid-19 bulletin, which is updated every evening by the directorate of health services, the reports from three districts – Changlang, East Siang and Capital Complex – are worthy of note in terms of detection of higher numbers of positive cases.
The samples collected from eastern Arunachal, including the Siang belt, are being sent to the Regional Medical Research Centre in Dibrugarh, Assam. The samples collected from the capital complex are being put through reverse transcription polymerase chain reaction (RT-PCR) and TrueNat tests at the Tomo Riba Institute of Health & Medical Sciences (TRIHMS), Naharlagun, and the intermediate reference laboratory in Naharlagun.
As per the latest update, Changlang has collected 2167 swab samples till Sunday. Out of these, 1506 tested negative, 55 tested positive, 15 tested positive in repeat test, and the results of 581 are awaited.
East Siang district has collected 1282 samples so far, out of which 1081 returned negative results, nine tested positive, 27 tested negative in repeat test, one tested positive in repeat test, and the results of 164 are awaited.
In the capital complex, a total of 4055 samples have been collected, out of which 3930 tested negative, five tested positive, 41 tested negative in repeat test, 12 tested positive in repeat test, and the results of 65 are awaited. Two persons have been discharged.
There is a stark contrast in the percentages of sample collection and the number of positive cases in Changlang and the capital complex. In spite of recording the highest number of sample collection, the positive cases in the capital complex are lower even than in East Siang.
Unverified sources informed that the first spike in positive cases was reported only after the health department had outsourced the samples to Dr Lal Pathlabs, New Delhi.
There was a report of the RT-PCR machine in the TRIHMS showing false negative results on a couple of occasions.
It is said that, in the case of the first Covid-19 positive person, from whom the sample was taken after 13 days, the result showed negative in the RT-PCR test, but surprisingly, the sample taken within the next 24 hours and put through the RT-PCR test returned an inconclusive result, and the next day – the 15th day – it tested negative again.
Similar fluctuations were also reportedly witnessed with the samples taken from the Chennai returnee positive patient. It is said that, in his case, on the fifth day of his admission to the TRIHMS, his first sample tested negative and the second sample (collected after 24 hours) tested positive again.
Scientifically, it is said, faulty techniques of sample collection or lack of quality control and cold chain maintenance of samples during transportation could be the reason behind false negative and fluctuating reports in the RT-PCR tests.
The health department recently procured a US-based company’s Thermo Fisher RT-PCR machine, which has been installed at the TRIHMS. It is understood that the department is considering purchasing CoV-2, a confirmatory kit which is considered to be more reliable.
If the reliability of the RT-PCR tests at the TRIHMS is questionable, the authority needs to review the quality control, as well as the effectiveness of the machine, as false negative results could turn out to be disastrous for the state.