The Arvind Kejriwal government was pulled up by the Delhi High Court today for making Rapid Antigen Test the primary test for coronavirus despite its high rate of false negative results. The court's tough questions brought Delhi's suddenly reducing number of positives under scrutiny. From several thousands daily a few weeks ago, the number of positives in Delhi has dropped below 1,000 -- a situation the Delhi government has flagged as a turnaround.
The RT-PCR -- which gives a positive result only if the virus is present in blood -- is considered the gold standard.
In contrast, the Rapid Antigen Test can zero in only on people who contracted the disease at least a fortnight ago and have developed antibodies in their bloodstream.
So while the test can accurately detect how far the infection has spread in an area, it cannot detect live cases and help contain the spread.
The High Court today questioned why Delhi, which is capable of conducting 11,000 RT-PCR tests a day, has not conducted more than 600 tests a day between July 15 and July 23.
Data analysed by NDTV shows that between June 18 and July 24, Delhi conducted 4,04,141 Rapid Antigen Tests. Among those tested, 2,818 symptomatic people who tested negative, went through an RT-PCR test. Of them, 404 people tested positive, indicating that the false negatives rate of Rapid Antigen Tests is 14 per cent.
The High Court has also questioned the policy of the Indian Council of Medical Research -- the nodal body in the battle against coronavirus -- to conduct the RT-PCR test only on the symptomatic people who test negative in the antigen test.
This would miss the genuine coronavirus cases, the court said, pointing out that a government survey recently showed that almost a quarter of the infected population was asymptomatic.
The court has asked ICMR to come up with a new advisory on testing and directed the Delhi government to give an updated status report of the tests carried out by August 4, the next date of hearing.
Delhi Health Minister Satyender Jain said there is "not much difference" between the two tests, though the RT-PCR test is considered more specific.
"The most important point is that fewer people are getting admitted to hospitals today and you will not find a single person who will say that he wanted to get a test but was unable to get it done," he added.