Silver lining despite Delhi case spike

TALLY UP BY 3,947 Total cases in Delhi at 66,602, of which 40% came in last 10 days; number of active cases reduces by 1,363 in last week

nNEW DELHI: Delhi on Tuesday recorded its largest single-day spike of coronavirus cases (Covid-19) so far with 3,947 people testing positive, although this number came on the back of a sharp increase in testing in the state — 16,952 samples were tested on Tuesday.

Tuesday’s spike took the tally in the city to 66,602, with more than 40% of these cases coming in just the last 10 days. The number of deaths touched 2,301, with 68 new fatalities reported in the last 24 hours, according to the Delhi government’s health bulletin.

However, an analysis of Delhi’s Covid-19 data by HT offered a much-needed silver lining. With the number of new recoveries and discharges picking up pace in the past few days, the number of active cases in the city have actually reduced by 1,363 in the last week. [Chart 1] That means Delhi has seen more recoveries than new cases.

Active cases — calculated by subtracting recovered patients and deaths from the tally — are a key metric to understand the weight of the caseload that hospitals have to handle. The relative stability in active cases traces its source to a recent boost in recovery numbers — nearly 62% of all recoveries have been reported in just the last 10 days.

The recent spike in cases also comes on the heels of testing in Delhi being ramped up using rapid antigen kits last Thursday, with the proportion of tests turning out positive beginning to decrease [Chart 2]. At 23.2%, this number, called the positivity rate, was still among the highest in the country in absolute terms on Tuesday, but it has been decreasing on an average over the past week.

The number of average daily tests more than doubled to 13,880 for the week ending June 23 compared to 6,200 the week before.

The new test kits, which give results within 30 minutes, are being used at 193 centres across Delhi’s 11 districts. To be sure, the use of the rapid tests has meant a relaxation of testing norms in Delhi, which experts said was expected to lead to drop in positivity rate. Earlier only people who had a history of contact with positive cases or those who showed symptoms were getting tested in the Capital, but under the rapid tests, all residents of Delhi’s containment zones will get tested.

The positivity rate for the week ending June 22 stood at 24%, meaning nearly one in every four people tested turned out positive. This number was 31% a week before. The number is still high in but it has begun to decline -- a clear indication that Delhi is finally beginning to test enough.

Covid deaths also appear to have stabilised over the past week, even as a massive spike is seen in new recoveries [Chart 3]. Even though there hasn’t been an official statement on the increase in the number of patients who have recovered or discharged, officials familiar with the matter said that this is due to Delhi aligning its discharge policy with the Union health ministry’s latest guidelines. As per the health ministry guidelines, mild to moderate Covid-19 patients can be discharged without testing on the 10th day of the symptoms appearing and/or three days after resolution of symptoms.

Delhi government said it is focussing on increased testing and containment zones. “An increase in testing have shown to decrease positivity rates worldwide. At the same time all our additional testing is focused completely on containment zones which tend to have infected patients as well. Overall, it looks like a result of additional testing and effective containment,” a Delhi government spokesperson said on Tuesday.

Experts, however, advised caution in reading into numbers just yet. “Positivity rates should not be used to predict the course of the infection in the city. This is because of two reasons. One, Delhi has just started using rapid antigen kits which does not give false positive reports but due to lower sensitivity than RT-PCR test must be missing some positive cases,” said Dr Shobha Broor, former head of the department of microbiology at AIIMS. “Two, there have been a lot of changes in the city’s testing strategy that is bound to affect the positivity rate,” she said.