Delhi is in the danger zone
The spike in Covid-19 infections is worrying. Enhance RT-PCR tests, be responsible
Delhi, on Wednesday, reported 5,673 Covid-19 cases, the highest single-day increase in cases ever recorded in the city by a large margin. On average, Delhi has reported 4,225 cases every day in the past week, which means the trajectory has now surpassed the previous peak of 4,174 reported for the week ending September 17. This rising case rate has come right at the start of the festive season and winter, which could intensify the spread. This peak has also been accompanied by a rise in the positivity rate. Nearly one in every 10 samples (9.4%) tested on Wednesday was positive, the highest since September. The seven-day average of positivity rate has increased two percentage points in the past two weeks — from 5.6% to 7.6%.
A fast-rising positivity rate typically suggests that a region is testing inadequately and is, thus, letting the virus get more prevalent. The positivity rate should drop to 5% or below if a region’s testing programme is adequate and is keeping the outbreak in control, according to the World Health Organization. While Delhi government is testing at near-peak levels (over 60,000 samples were tested on Wednesday), it is clearly not enough. When Delhi improved its testing in early September, it relied heavily on rapid antigen tests to boost those numbers. Antigen tests are cheap, and give results within 15 minutes, but the downside is they can miss as many as half the infected people. Delhi, in fact, is among a handful of major states where antigen tests constitute more than two-thirds of daily tests. This heavy-handed use of antigen tests may have even suppressed a much higher positivity rate. The alternative is the gold standard RT-PCR molecular tests, which are more expensive and time-consuming, but significantly better at finding the infection.
This makes the road map clear. First, Delhi must improve testing, in overall numbers as well in the share of RT-PCR tests. Not only will that narrow down on cases and bring down the positivity rate, it will also provide more credible data. Second, there is no alternative to stronger citizen compliance to social distancing norms. Delhi is one of the only regions in the country that has seen distinct waves of infections, much like the West, where governments are reinforcing curbs. Restrictions are not desirable, given the economic costs, but this hinges on citizens behaving responsibly.