Delhi still lagging in gold standard of Covid testing

New Delhi: Over the past one week, there hasn’t been any significant increase in the number of tests being conducted using RT-PCR, which is considered the gold standard for Covid-19 testing. Data shared by the state health department showed that the total number of tests conducted using RT-PCR over the past eight days, from September 16 to 22, hovered between 8,828 (on September 21) and 11,322 (September 20).

Currently, Delhi has a capacity of conducting nearly 15,000 RT-PCR tests daily. On September 16, Delhi High Court had suggested that the AAP government increase the RT-PCR testing capacity to the maximum possible as rapid antigen tests were only 60% accurate.

On Wednesday, when Delhi recorded 3,714 new cases, the number of tests over the past 24 hours stood at 59,580. Of this, 10,359 tests (17%) were done using RT-PCR/CBNAAT/TrueNat, while the remaining 49,221 (83%) were conducted using rapid antigen tests (RAT), which has a lower sensitivity.

Before this, from September 16 to 22, RT-PCR/CBNAAT/TrueNat tests conducted in Delhi stood at 11,275, 9,564, 11,203, 10,681, 11,322, 8,828 and 9,459, respectively.

Public health specialists said RT-PCR tests needed to be scaled up for more effective tracing and tracking of Covid-19 cases. “In case of RAT, which is easier to perform compared with RT-PCR, chances of false negatives are much higher. Such people may continue to spread the disease,” said a specialist.

Till date, over 2.56 lakh cases of Covid-19 have been recorded in Delhi. In all, 5,087 people have died due to the infection, including 36 fatalities over the past 24 hours. Testing needs to be ramped up for timely diagnosis so that people testing positive are offered the right treatment at the earliest, doctors say.

In mid-June, the number of RT-PCR tests being conducted daily was 5,000-6,000, which has gone up to 11,000 a day now. Delhi government, sources said, was working out the modalities for making and rolling out an expansion plan. On the ground, RT-PCR demands more manpower compared with RAT.

“Antigen tests do not require high skills because health workers need to follow simple techniques to get the results, which are out within 15 to 30 minutes. But RT-PCR samples cannot be analysed using a RAT-like kit. The samples need to be properly packed and transported to the testing centres. Improper handling can result in labs giving inconclusive results,” said an official, adding that manpower was a less difficult challenge.

RAT was introduced on June 18. Initially, it was used for testing in containment zones. Later, in mid-July, as more kits were made available by the government, the health department expanded testing through this method to multiple points across all 11 revenue districts in the capital to scale up testing.