Delhi records most new Covid cases in 5 days, but testing dips yet again
Delhi reported the highest number of new coronavirus disease (Covid-19) cases in five days on Wednesday, even as testing fell by over 2,000 from the previous day. The Capital added 2,871 new cases of the viral infection on Wednesday, pushing the positivity rate back over 5% after a single day dip.
Positivity rate is the fraction of samples that test positive among total tested and reflects the trends in ongoing transmission.
According to recommendations by the World Health Organization (WHO), the positivity rate from a region that has a comprehensive testing programme should be at or below 5% for at least two weeks before it can be considered that the outbreak is under control in the region.
The positivity rate on Wednesday stood at 5.57%, an increase from 4.99% a day before — the first time in several months that the number fell below 5%.
Even though the number of new cases have declined from the peak of around 4,400 cases in mid-September, the city continues to report an average of 2,627 cases over the week. The number of tests, however, have gone down since then. In the 11 days between September 9 and 19, when the Capital added a daily average of 4,160 new cases, the city collected a daily average of 58,485 samples for Covid-19 tests. However, around 49,000 tests for detecting the infection were done during the last seven days, while over 54,600 were done the week before that.
The number of RT-PCR tests, considered the most accurate diagnosis of the infection, dropped marginally as well on Wednesday. In any case, the gold standard tests only account for 18% of the total tests. The rapid antigen tests that are widely used are cheap, easy to perform and give results within 15 minutes. However, they are more likely to throw false negatives.
On average 9,232 RT-PCR tests were performed over the last seven days as compared to an average of 10,203 a week before. The Delhi high court had rapped the government for not using its entire capacity of 14,000 RT-PCR tests a day.
The Delhi government had also communicated to the district authorities in the third week of September that there should be no lapse in testing every symptomatic person using the RT-PCR method. This came after they found data of 1,400 symptomatic people who were not checked using the more accurate test.
“The RT-PCR test is more accurate and will be better reflective of the situation on the ground. If the number of cases are going up or down we will come to know if we are performing a lot of RT-PCR tests. The rapid antigen tests did help in scaling up, but there are set guidelines for where these tests should be done and that has to be adhered to,” said Dr Lalit Kant, former head of the department of epidemiology and infectious diseases at ICMR.
“The number of cases might have gone down for now, but there should be no laxity in control measures. This is because the cases of most respiratory illnesses go up during the winters – people are in close proximity within enclosed spaces increasing the risk of transmission. The immunity also goes down when there is a dip in temperature making people more susceptible to all kinds of infections,” said Dr Neeraj Gupta, head of the department of pulmonary medicine at Safdarjung hospital.