Delhi govt asks hospitals to conduct more antigen tests

Almost 80% of the tests conducted in Delhi over the past seven days were the more accurate RT-PCR tests.

After a recent Indian Council of Medical Research (ICMR) testing advisory recommended that states increase the number of faster rapid antigen tests (RAT) amid a surge in cases of the coronavirus disease (Covid-19), the Delhi government has directed all its hospitals to conduct the tests at their flu corners, fever clinics, and emergency departments round the clock.

ICMR on Tuesday issued the fresh Covid-19 testing advisory recommending the conducting of antigen tests, a deviation from its previous policy of ensuring that at least 70% of tests conducted are done using the more accurate and gold-standard RT-PCR. (Bloomberg | Representational image)

The tests will also be conducted on Sundays and other national holidays, according to an order by principal health secretary Dr Ashish Chandra Verma.

Almost 80% of the tests conducted in Delhi over the past seven days were the more accurate RT-PCR tests.

The RT-PCR test amplifies the genetic material of the virus to detect an infection, and hence is more accurate than the rapid antigen test, which detects the presence of viral proteins on the swab sample without any amplification.

But daily testing numbers have reduced in the capital over the past three weeks, shows the data from the state daily health bulletin. Delhi tested 114,000 people on April 10, the highest figure for the city till date. The numbers have declined since then and on Thursday, Delhi conducted 78,780 tests. The use of more RATs may boost testing, though they do throw up more “false negatives”. “

RAT has a shorter turnaround time -- of 15 to 30 minutes -- and thus offers a distinct advantage of quick detection of cases and opportunity to isolate and treat them early for curbing transmission and for favourable outcome,” the order from Verma read.

The order also directed all hospitals to ensure that a follow-up test, the more accurate RT-PCR test, is done only for symptomatic persons whose RAT is negative. “It is reiterated that all teams must adhere to the ICMR norms …follow up RT-PCR testing of symptomatic individuals detected as “negative” by the rapid test and updation of results on ICMR portal in a timebound manner,” the order read.

ICMR on Tuesday issued the fresh Covid-19 testing advisory recommending the conducting of antigen tests, a deviation from its previous policy of ensuring that at least 70% of tests conducted are done using the more accurate and gold-standard RT-PCR.

Currently, ICMR approves RAT kits if they have a sensitivity of 50%, meaning that the test might actually give a false negative report for as many as half the positive cases. However, a positive RAT result is considered accurate.