Gurugram: Number of pending samples brought down by nearly 55%

The number of samples awaiting confirmatory tests for Covid-19 infection in the district has been reduced by 55% over the past five days, said officials of the district

The number of samples awaiting confirmatory tests for Covid-19 infection in the district has been reduced by 55% over the past five days, said officials of the district health department. Since July 1, the number of samples has incrementally built up due to a paucity of equipment and logistical challenges in reporting the test results. However, with the addition of the new generation of reverse transcription polymerase chain reaction (RT-PCR) test kits, the backlog of pending samples is gradually being cleared, with the number of pending samples down to 614 from 1,358 on Saturday. This backlog too would be cleared soon, said health officials.

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Dr Virender Yadav, chief medical officer (CMO), Gurugram, said that the health department has begun using three new RT-PCR kits. Each test kit has a cycle time of about three hours, while the labs can run two to three cycles daily. “We can test up to 90 samples at a time using the new test kits, which can produce results in about three hours. This has allowed us to test 600 new samples each day, and, more importantly, report the results sooner. Traditionally, RT-PCR can take at least 12 hours to produce a confirmatory result,” Yadav said.

RT-PCR tests are considered to be the gold standard of Covid-19 testing and are used to determine the amount of viral RNA in a sample. Health department officials, however, did not provide details on the make, sensitivity or specificity of the new RNA test kits. “I am unable to recall these details at the moment. However, the new test kits have been validated and provided to us by the Indian Council of Medical Research (ICMR),” said Dr Jai Prakash Sharma, the Integrated Disease Surveillance Programme’s (IDSP) district surveillance officer in Gurugram.

Sharma added that there are only about 44 samples collected prior to July 23 whose test results are awaited. “Of the current lot of 614 pending samples, almost 570 were collected on July 23 itself, and their results will be received by late in the night, and shared in the next day’s (Friday) bulletin,” Sharma said, emphasizing that the new kits have significantly improved the turnaround time in reporting results. From the earlier turnaround time of nearly 12 hours, the new test kits are being able to provide results in three hours.

A doctor with the IDSP in Gurugram, seeking anonymity, explained that the introduction of rapid antigen detection tests in the city earlier this month had necessitated an upgrade in health department’s RT-PCR testing capacity. “About 10% of the antigen test samples are being retested via RT-PCR. As per the norms, in antigen testing, a positive test is always a true positive, while a negative test requires a follow-up test, via the RT-PCR method, especially if a patient is showing symptoms. This adds to the RT-PCR’s testing load by anything between 80 to 100 samples per day, which is why the backlog had initially built up.”

Officials said that, on an average, about 1,500 to 1,700 samples are being tested in the district everyday, of which rapid antigen tests make up about two third of the total number of tests. These tests are being conducted in the large outbreak regions and containment zones. The health department’s target in the coming weeks is to increase this capacity to at least 2,000 tests per day, if not more.

A total of 74,720 tests have been carried out in Gurugram so far (including both anitgen and RT-PCR tests). While it took three and a half months for the health department to carry out the first 50,000 tests (which it achieved on July 10), the subsequent 24,000 odd tests have been carried out in less than two weeks.