Covid-19 tests in Delhi gradually declining again
The proportion of RT-PCR tests, considered the gold standard for Covid-19 diagnosis, however, has remained high despite the dip in overall tests.Updated: Oct 11, 2020, 05:14 IST
Testing for the coronavirus disease (Covid-19) in Delhi appears to be slowly dropping from its peak levels again, even as new infections in the Capital continue to go down after a spike in cases a month ago forced the Delhi government to ramp up testing.
The proportion of RT-PCR tests, considered the gold standard for Covid-19 diagnosis, however, has remained high despite the dip in overall tests.
Delhi conducted 59,368 daily tests on average for the week ending September 20, what has been the city’s highest recorded rate of testing till date. Since then, this number dropped to 49,102 in the past week — down by around 17%. In the same period, the national average of daily tests increased from 1,021,881 tests a day to 1,135,471 — an increase of around 11%.
To be sure, the national capital reported a near three-fold increase in testing in September from levels in July and August after Delhi chief minister Arvind Kejriwal held an emergency meeting in the final week of August to address the resurgence of cases in the city. The CM said then that the government would at least double daily tests to 40,000 a day, but the government ended up boosting testing to nearly 60,000 a day at its peak. However, since September 20, the testing numbers have seen a near-steady decline.
Despite this decline, the proportion of RT-PCR tests has not dropped. On average, nearly 20% of tests conducted in the last week have been RT-PCR. This is the highest this proportion has been in nearly a month – 21% of tests were RT-PCR for the week ending September 12.
On Saturday, Delhi added 2,866 cases of Covid-19, taking the total number of infections in the city to 306,559. Daily deaths, meanwhile, continued to rise with 48 new fatalities reported on Saturday taking the total deaths in the city to 5,740.
Delhi’s health minister Satyendar Jain said: “Delhi government has set up adequate number of test centres with all necessary facilities. We can assure you that no individual who wants to get tested for Covid-19 is sent back at any of these test centres. Chief minister Arvind Kejriwal has continuously been urging people to get tested. In the coming days, we are going to intensify the Covid-19 awareness campaign, aiming at encouraging more people to get themselves tested.”
“As for the RT-PCR tests, we are following the ICMR guidelines. We are using the rapid antigen test in the containment zones, all the symptomatic patients who test negative are re-tested using RT PCR. Anyone who asks for it can also get it. The number of tests conducted will depend on the number of tests needed, no matter what our capacity is,” said Jain.
Dr Lalit Kant, former head of epidemiology at the Indian Council of Medical Research (ICMR), said: “Delhi has a population of 20 million and the number of people who have had the infection is still very small. High level of testing has to be sustained till there is a low pool of susceptible population or a vaccine is available,” he said.
“The general rule of thumb to check whether testing is adequate is a sustained positivity rate of 5% or less. What are you testing with matters as well? The ICMR testing strategy has to be followed. Anyone outside the containment zones have to be tested using RT-PCR which is much more accurate. Another thing we need to see is that how many tests are needed for us to find one positive cases. If that number is coming down, then we aren’t testing enough. In Delhi, this number stands at just about 17 to 18 per cent, this should at least be 30. Some of the countries conduct about 200 tests to get one positive case,” said Dr Kant.