New Covid-19 cases touch 26-day high in Delhi as RT-PCR tests rise
Delhi reported 3,686 new Covid-19 infections on Wednesday, the highest in 26 days, taking the total number of infections in the city to 340,436. The national capital recorded 47 new Covid-19 fatalities taking the total death toll in the city to 6,128.Updated: Oct 22, 2020, 06:45 IST
The Delhi government on Wednesday conducted 16,629 RT-PCR tests, the highest ever in a single day of the more accurate tests that are considered gold standard for detection of the coronavirus disease (Covid-19).
Delhi reported 3,686 new Covid-19 infections on Wednesday, the highest in 26 days, taking the total number of infections in the city to 340,436. The national capital recorded 47 new Covid-19 fatalities taking the total death toll in the city to 6,128.
The number of cases of the infection has been on the rise again in the city, with over 3,000 cases being reported each day in the last week, barring Sunday, when comparatively lesser number of tests were conducted.
The record in the number of real-time polymerase chain reaction, or RT-PCR tests, continues a recent trend of increasing share of these tests. RT-PCR tests accounted for 28% of the total 59,064 tests conducted in past 24 hours.
Over the past week, more than 27% of the tests were done using this method up from just about 18% in September when the Delhi government had massively scaled up testing along with the rising cases of the infection. Now, the government has been ramping up the RT PCR tests over the last two weeks.
The Delhi high court had earlier questioned the government on why the more accurate RT-PCR tests were not being performed to full capacity. The alternate rapid antigen tests are cheap, easily deployable in clinics and dispensaries, and gives results within 15 minutes. However, the downside is that they can give false negatives, or miss positive cases.
Since RT-PCR tests have a higher sensitivity, their increased use by the Delhi government has led to an increase in number of cases and positivity rate – the proportion of samples that return positive among total tested.
An average positivity rate of 6.2% was recorded in the last seven days as compared to 5.5% the week before. During the last seven days, 3,269 new cases were reported each day on average as compared to 2,777 cases the week before.
However, the number of hospital admission have remained almost the same during the last two weeks when the number of cases went up, indicating that more asymptomatic cases were detected using the RT PCR tests.
“The sensitivity of an RT-PCR test is much higher than that of a rapid antigen test, so it will pick up more cases. This is the reason any symptomatic person who tests negative on the rapid test must get an RT-PCR for confirmation. So, if you increase the number of RT-PCR tests, the number of cases and positivity rate is likely to go up,” said Dr GC Khilnani, former head of the department of pulmonology at the All India Institute of Medical Sciences (AIIMS).