Delhi records 4,473 new Covid-19 cases, active cases breach 30K mark

The number of cases continued its upwards surge in the city, with Delhi recording its highest number of new Covid-19 cases in a day – 4,473 – on Wednesday, as per the daily health bulletin released by the state government. So far, over 2, 30,000 people have been affected by the viral infection.

The new cases on Wednesday also pushed the number of active cases or those currently living with Covid-19 over the 30,000 mark for the first time. As on Tuesday, 30,914 people were living with the infection either in home isolation, Covid care centres, or hospitals. At its peak during the surge in cases in June, the number of active cases recorded had been just over 28,000.

In fact, the number of active cases has almost tripled in the last one month.

At the same time, although the absolute number of hospitalisations in the city has gone down, but the proportion of active cases being hospitalised has declined. In mid-August, just over 32% of around 10,800 active cases were in hospitals. At present, 21.9% of the 30,914 patients are in hospitals, shows the Delhi government data.

The increase in the number of hospitalisations – especially in the intensive care units – has resulted in the Delhi government asking three of its hospitals to scale up their ICU facilities and 33 big private hospitals to reserve 80% of its total ICU beds for the treatment of Covid-19 patients.

“This could possibly be because of a high number of tests are detecting more asymptomatic cases or those with mild symptoms that can be managed in home isolation itself. However, the absolute numbers are on the rise because now most doctors admit patients early on and sometimes for observation as it has shown to reduce mortality,” said Dr Neeraj Gupta, professor from the department of pulmonology at Safdarjung hospital.

The increase in the number of cases being reported from the city is the high number of tests being conducted. Delhi conducted 62,593 tests, according to the government bulletin, just 76 tests short of its record high reported on Tuesday.

However, the number of the more accurate RT-PCR test was the highest on Wednesday – 11,275 or 18% of the total tests reported were done using this method. The Delhi high court on Wednesday directed the government to increase the number of RT-PCR tests being conducted in the city. The rapid antigen tests are known to be less accurate than RT-PCR and throw up more false positives.

After the introduction of the rapid antigen tests, which is cheaper and faster, in mid-June when the city had last seen a surge in the number of Covid-19 cases the number of RT-PCR tests had slowly gone down, with most government centres testing only the symptomatic people who tested negative on the rapid test using RT PCR.

The ratio of RT-PCR and Rapid Antigen fell from 39% in August-end to as low as 15% on September 10 as the government more than doubled the number of tests being conducted in the city.

Even with the higher number of tests, however, the positivity rate – the fraction of samples that return positive among the total tested – has still not gone below 7%. The average daily positivity rate over the last seven days was 7.18%.

The spread of the infection is thought to be in control if the positivity rate in an area remains below 5% for at least two weeks.

“This disease has been very unpredictable and there is no way to tell whether till when the number of cases will go up. However, I think the numbers are likely to remain high as of now and further increase in the winters when people huddle together and live in closed spaces together leading to more transmission,” said Dr Shobha Broor, former head of the department of microbiology at All India Institute of Medical Sciences.

She said, increasing the number of RT-PCR tests is not practically possible. “We have to see what the tests are being used for. If it is for surveillance to estimate how many people in an area have the infection, we already know the percentage of false negatives it throws up so we can multiply it by the error factor and estimate the number of cases. If it is for clinical diagnosis, if a person tests negative on the RT PCR test but the doctors suspect it to be Covid-19, the person can be retested using the more accurate RT-PCR test. This is because it is practically not possible to scale up the number of RT PCR tests to such a high level,” said Dr Broor.